Polydienes And Diene Copolymers Having Organophosphine Functionality

ABSTRACT

Embodiments provide polydienes and diene copolymers having organophosphines functionality. Specific embodiments employ phosphorus-containing organometal initiators and copolymers prepared by anionically polymerizing conjugated diene monomer and vinyl organophosphine.

This application claims the benefit of U.S. Provisional Application Ser.No. 61/640,915, filed on May 1, 2012, and U.S. Provisional ApplicationSer. No. 61/779,399, filed on Mar. 13, 2013, which are incorporatedherein by reference.

FIELD OF THE INVENTION

Embodiments of the present invention provide polydienes and dienecopolymers having organophosphines functionality. Specific embodimentsare directed toward the preparation of functional polymers by employingphosphorus-containing organometal initiators. Other specific embodimentsprovide copolymers prepared by anionically polymerizing conjugated dienemonomer and vinyl organophosphine.

BACKGROUND OF THE INVENTION

Anionic polymerization techniques have been used to synthesize polymersthat are useful in the manufacture of tires. Using these techniques,certain organometallic compounds can be used to initiate thepolymerization of monomer such as conjugated diene monomer. Due to themechanism by which the initiation and polymerization proceeds, theorganometallic compound adds to monomer to form a polymer chain whereinthe organo substituent of the initiator is attached as the head group ofthe polymer. Common initiators include organo lithium species such asn-butyl lithium.

Certain initiators impart a functional group to the polymer. Thesefunctional groups may include a heteroatom or metal that can have adesirable impact on the polymer or compositions containing the polymer.For example, where the polymers are employed in the manufacture of tiretreads, the functional group can lower the hysteresis loss of the treadvulcanizate. This lowering of hysteresis loss may result frominteraction between the functional group and the filler, although othermechanisms have also been proposed.

Tributyl tin lithium compounds have been used to initiate conjugateddienes (optionally together with copolymerizable monomer) to formvulcanizable polymers (i.e., rubber) that, when used in treads, has adesirable impact on the performance of the tread. Likewise, lithiatedcyclic imines (e.g., lithio hexamethyleneimine) have also been used toinitiate the polymerization of similar polymers and provide rubber withdesirable performance in tire treads. Still other examples includelithiated thioacetals (e.g., 2-lithio-1,3-dithianes). Still further, theuse of lithium dialkylphosphines in conjunction with phosphine oxidemodifiers have been proposed.

The selection of useful initiator compounds, however, is not trivial.This is especially true where there is a desire to select initiatorcompounds that have a desirable impact on filled rubber compositions orvulcanizates, such as tire treads. Indeed, the prior art only includes afew types of compounds that are useful. This difficulty derives fromseveral factors. For example, the anionic polymerization of conjugateddienes is sensitive, and many compounds or substituents can poison thepolymerization system. And, the selection of substituents or functionalgroups that can impact filled compositions, such as tire treads, isdifficult to predict.

Because functional initiators remain desirable, particularly for thesynthesis for functionalized polymers that are used in the manufactureof tires, there is a continued desire to identify initiators that canlead to technologically useful polymers and that have desirable impacton filled rubber compositions and/or vulcanizates.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a method forpreparing a functionalized polymer, the method comprising: polymerizingconjugated diene monomer, optionally together with comonomer, using aphosphorus-containing organometal initiator.

Other embodiments of the present invention provide a method forpreparing a polymer, the method comprising: preparing an initiator byreacting a vinyl organophosphine with an organometal compound; andpolymerizing conjugated diene monomer, optionally together withcomonomer, by initiating the polymerization of the monomer with theinitiator.

Still other embodiments of the present invention provide afunctionalized polymer defined by the Formula V:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group.

Yet other embodiments provide a functionalized polymer defined by theFormula VI:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group.

Other embodiments of the present invention provide a process forpreparing a copolymer including one or more phosphorus-containing merunits, the process comprising anionically polymerizing conjugated dienemonomer, vinyl organophosphine monomer, and optionally monomercopolymerizable therewith.

Still other embodiments of the present invention also provide acopolymer having one or more phosphorus-containing mer units defined bythe formula VII:

where R¹¹ and R¹² are each independently monovalent organic groups, orwhere R¹¹ and R¹² join to form a divalent organic group, and where R¹³,R¹⁴, and R¹⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group.

Other embodiments provide a copolymer having one or morephosphorus-containing mer units defined by the formula VIII:

where R¹¹ and R¹² are each independently monovalent organic groups, orwhere R¹¹ and R¹² join to form a divalent organic group, and where R¹³,R¹⁴, and R¹⁵ are each independently hydrogen or monovalent organicgroups, or where R¹³ and R¹⁴ join to form a divalent organic group.

Still other embodiments of the present invention provide afunctionalized polymer defined by the Formula IX:

where π is a polymer chain, α is a functional group or hydrogen atom,R¹¹ and R¹² are each independently monovalent organic groups, or whereR¹¹ and R¹² join to form a divalent organic group, and where R¹³, R¹⁴,and R¹⁵ are each independently hydrogen or monovalent organic groups, orwhere R¹³ and R¹⁴ join to form a divalent organic group.

And other embodiments of the present invention provide a functionalizedpolymer defined by the Formula X:

where π is a polymer chain, α is a functional group or hydrogen atom,R¹¹ and R¹² are each independently monovalent organic groups, or whereR¹¹ and R¹² join to form a divalent organic group, and where R¹³, R¹⁴,and R¹⁵ are each independently hydrogen or monovalent organic groups, orwhere R¹³ and R¹⁴ join to form a divalent organic group.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the present invention are based, at least in part, on thediscovery of polydienes and diene copolymers that include anorganophosphine functionality. Certain aspects of the present inventionare based, at least in part, on the discovery of a method for initiatingthe anionic polymerization of diene monomer, optionally together withcomonomer, using phosphorus-containing organometal compounds. While theprior art contemplates the use of lithium dialkyl phosphides, which arelithiated phosphines, the present invention employs an initiator wherethe phosphorus atom is directly bonded to a carbon atom. As a result, itis believed that the polymers produced by practice of the presentinvention have a phosphorus-containing headgroup that is more stablethan those proposed in the prior art. Other aspects of the presentinvention are based, at least in part, on the discovery of copolymers ofconjugated diene, vinyl organophosphine, and optionally monomercopolymerizable therewith prepared by anionic polymerization techniques.These copolymers are advantageously linear and have a relatively lowmolecular weight distribution. Thus, while the prior art contemplatesthe copolymerization of dienes and vinyl organophosphines using radicalpolymerization, the ability to copolymerize these monomer using anionicpolymerization techniques offers several advantages. In one or moreembodiments, the vinyl organophosphine monomer is charged aftersubstantial polymerization of the primary monomer (i.e., the conjugateddiene monomer), and therefore the resulting copolymer includesend-functionalization resulting from the addition of the vinylorganophosphine monomer at the chain end.

Vinyl Organophosphine

One or more embodiments of the present invention employ vinylorganophosphines, which may also be referred to as vinyl organophosphinemonomer or simply vinyl phosphines. In one or more embodiments, vinylorganophosphines may be defined by the formula I:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, and where R³, R⁴,and R⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group. In particularembodiments, R³, R⁴, and R⁵ are hydrogen atoms.

In one or more embodiments, the monovalent organic group is ahydrocarbyl group or substituted hydrocarbyl group. Examples ofhydrocarbyl groups or substituted hydrocarbyl groups include, but arenot limited to, alkyl, cycloalkyl, substituted cycloalkyl, alkenyl,cycloalkenyl, aryl, substituted aryl groups, and heterocyclic groups.The hydrocarbyl group may contain heteroatoms such as, but not limitedto, nitrogen, oxygen, silicon, tin, sulfur, boron, and phosphorousatoms. In one or more embodiments, the monovalent organic group mayinclude at least 1, or the minimum number of carbon atoms required toform a group, up to about 12 carbon atoms. The term substituted is usedin its conventional sense to refer to organic groups, such as alkylgroups, that replace a hydrogen atom in a parent organic group.

In one or more embodiments, types of vinyl organophosphines includevinyldihydrocarbyl phosphines,dihydrocarbyl(2,2-dihydrocarbyl-1-hydrocarbylvinyl)phosphines,dihydrocarbyl(2,2-dihydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbyl-1-hydrocarbylvinyl)phosphines, anddihydrocarbyl(1-hydrocarbylvinyl)phosphines.

Specific examples of vinyldihydrocarbyl phosphines includevinyldiphenylphosphine, vinyldicyclohexylphosphine,vinyldicyclopentylphosphine, vinyldimethylphosphine,vinyldiethylphosphine, vinyldi-n-propylphosphine,vinyldi-t-butylphosphine, vinyldi-n-octylphosphine,vinyldi-n-dodecylphosphine, vinyldipiperidylphosphine,vinyldipyrrolidylphosphine, vinyldipyridylphosphine, andvinyldipyrrylphosphine.

Specific examples ofdihydrocarbyl(2,2-dihydrocarbyl-1-hydrocarbylvinyephosphines includedimethyl(2,2-diphenyl-1-methylvinyl)phosphine,diethyl(2,2-diphenyl-1-methylvinyl)phosphine,di-n-propyl(2,2-diphenyl-1-methylvinyl)phosphine,di-t-butyl(2,2-diphenyl-1-methylvinyl)phosphine,di-n-octyl(2,2-diphenyl-1-methylvinyl)phosphine,di-n-dodecyl(2,2-diphenyl-1-methylvinyl) phosphine,diphenyl(2,2-diphenyl-1-methylvinyl)phosphine,dicyclohexyl(2,2-diphenyl-1-methylvinyl)phosphine,dicyclopentyl(2,2-diphenyl-1-methylvinyl)phosphine,dipiperidyl(2,2-diphenyl-1-methylvinyl)phosphine,dipyrrolidyl(2,2-diphenyl-1-methylvinyl)phosphine,dipyridyl(2,2-diphenyl-1-methylvinyl)phosphine,dipyrryl(2,2-diphenyl-1-methylvinyl)phosphine,dimethyl(2,2-diethyl-1-ethylvinyl)phosphine,diethyl(2,2-diethyl-1-ethylvinyl)phosphine,di-n-propyl(2,2-diethyl-1-ethylvinyl)phosphine,di-t-butyl(2,2-diethyl-1-ethylvinyl)phosphine,di-n-octyl(2,2-diethyl-1-ethylvinyl)phosphine,di-n-dodecyl(2,2-diethyl-1-ethylvinyl)phosphine,diphenyl(2,2-diethyl-1-ethylvinyl)phosphine,dicyclohexyl(2,2-diethyl-1-ethylvinyl)phosphine,dicyclopentyl(2,2-diethyl-1-ethylvinyl)phosphine,dipiperidyl(2,2-diethyl-1-ethylvinyl)phosphine,dipyrrolidyl(2,2-diethyl-1-ethylvinyl)phosphine,dipyridyl(2,2-diethyl-1-ethylvinyl)phosphine,dipyrryl(2,2-diethyl-1-ethylvinyl)phosphine,dimethyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,diethyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,di-n-propyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,di-t-butyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,di-n-octyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,di-n-dodecyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,diphenyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dicyclohexyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dicyclopentyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dipiperidyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dipyrrolidyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dipyridyl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dipyrryl(2,2-dicyclohexyl-1-propylvinyl)phosphine,dimethyl(2,2-dipyridyl-1-ethylvinyl)phosphine,diethyl(2,2-dipyridyl-1-ethylvinyl)phosphine,di-n-propyl(2,2-dipyridyl-1-ethylvinyl)phosphine,di-t-butyl(2,2-dipyridyl-1-ethylvinyl)phosphine,di-n-octyl(2,2-dipyridyl-1-ethylvinyl)phosphine,di-n-dodecyl(2,2-dipyridyl-1-ethylvinyl)phosphine,diphenyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dicyclohexyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dicyclopentyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dipiperidyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dipyrrolidyl(2,2-dipyridyl-1-ethylvinyl)phosphine,dipyridyl(2,2-dipyridyl-1-ethylvinyl)phosphine, anddipyrryl(2,2-dipyridyl-1-ethylvinyl)phosphine.

Specific examples of dihydrocarbyl(2,2-dihydrocarbylvinyl)phosphinesinclude dimethyl(2,2-diphenylvinyl)phosphine,diethyl(2,2-diphenylvinyl)phosphine,di-n-propyl(2,2-diphenylvinyl)phosphine,di-t-butyl(2,2-diphenylvinyl)phosphine,di-n-octyl(2,2-diphenylvinyl)phosphine,di-n-dodecyl(2,2-diphenylvinyl)phosphine,diphenyl(2,2-diphenylvinyl)phosphine,dicyclohexyl(2,2-diphenylvinyl)phosphine,dicyclopentyl(2,2-diphenylvinyl)phosphine,dipiperidyl(2,2-diphenylvinyl)phosphine,dipyrrolidyl(2,2-diphenylvinyl)phosphine,dipyridyl(2,2-diphenylvinyl)phosphine,dipyrryl(2,2-diphenylvinyl)phosphine,dimethyl(2,2-diethylvinyl)phosphine, diethyl(2,2-diethylvinyl)phosphine,di-n-propyl(2,2-diethylvinyl)phosphine,di-t-butyl(2,2-diethylvinyl)phosphine,di-n-octyl(2,2-diethylvinyl)phosphine,di-n-dodecyl(2,2-diethylvinyl)phosphine,diphenyl(2,2-diethylvinyl)phosphine,dicyclohexyl(2,2-diethylvinyl)phosphine,dicyclopentyl(2,2-diethylvinyl)phosphine,dipiperidyl(2,2-diethylvinyl)phosphine,dipyrrolidyl(2,2-diethylvinyl)phosphine,dipyridyl(2,2-diethylvinyl)phosphine,dipyrryl(2,2-diethylvinyl)phosphine,dimethyl(2,2-dicyclohexylvinyl)phosphine,diethyl(2,2-dicyclohexylvinyl)phosphine,di-n-propyl(2,2-dicyclohexylvinyl)phosphine,di-t-butyl(2,2-dicyclohexylvinyl)phosphine,di-n-octyl(2,2-dicyclohexylvinyl)phosphine,di-n-dodecyl(2,2-dicyclohexylvinyl)phosphine,diphenyl(2,2-dicyclohexylvinyl)phosphine,dicyclohexyl(2,2-dicyclohexylvinyl)phosphine,dicyclopentyl(2,2-dicyclohexylvinyl)phosphine,dipiperidyl(2,2-dicyclohexylvinyl)phosphine,dipyrrolidyl(2,2-dicyclohexylvinyl)phosphine,dipyridyl(2,2-dicyclohexylvinyl)phosphine,dipyrryl(2,2-dicyclohexylvinyl)phosphine,dimethyl(2,2-dipyridylvinyl)phosphine,diethyl(2,2-dipyridylvinyl)phosphine,di-n-propyl(2,2-dipyridylvinyl)phosphine,di-t-butyl(2,2-dipyridylvinyl)phosphine,di-n-octyl(2,2-dipyridylvinyl)phosphine,di-n-dodecyl(2,2-dipyridylvinyl)phosphine,diphenyl(2,2-dipyridylvinyl)phosphine,dicyclohexyl(2,2-dipyridylvinyl)phosphine,dicyclopentyl(2,2-dipyridylvinyl)phosphine,dipiperidyl(2,2-dipyridylvinyl)phosphine,dipyrrolidyl(2,2-dipyridylvinyl)phosphine,dipyridyl(2,2-dipyridylvinyl)phosphine, anddipyrryl(2,2-dipyridylvinyl)phosphine.

Specific examples of dihydrocarbyl(2-hydrocarbylvinyl)phosphines includedimethyl(2-phenylvinyl)phosphine, diethyl(2-phenylvinyl)phosphine,di-n-propyl(2-phenylvinyl)phosphine, di-t-butyl(2-phenylvinyl)phosphine,di-n-octyl(2-phenylvinyl)phosphine,di-n-dodecyl(2-phenylvinyl)phosphine, diphenyl(2-phenylvinyl)phosphine,dicyclohexyl(2-phenylvinyl)phosphine,dicyclopentyl(2-phenylvinyl)phosphine,dipiperidyl(2-phenylvinyl)phosphine,dipyrrolidyl(2-phenylvinyl)phosphine, dipyridyl(2-phenylvinyl)phosphine,dipyrryl(2-phenylvinyl)phosphine, dimethyl(2-ethylvinyl)phosphine,diethyl(2-ethylvinyl)phosphine, di-n-propyl(2-ethylvinyl)phosphine,di-t-butyl(2-ethylvinyl)phosphine, di-n-octyl(2-ethylvinyl)phosphine,di-n-dodecyl(2-ethylvinyl)phosphine, diphenyl(2-ethylvinyl)phosphine,dicyclohexyl(2-ethylvinyl)phosphine,dicyclopentyl(2-ethylvinyl)phosphine,dipiperidyl(2-ethylvinyl)phosphine, dipyrrolidyl(2-ethylvinyl)phosphine,dipyridyl(2-ethylvinyl)phosphine, dipyrryl(2-ethylvinyl)phosphine,dimethyl(2-cyclohexylvinyl)phosphine,diethyl(2-cyclohexylvinyl)phosphine,di-n-propyl(2-cyclohexylvinyephosphine,di-t-butyl(2-cyclohexylvinyl)phosphine,di-n-octyl(2-cyclohexylvinyl)phosphine,di-n-dodecyl(2-cyclohexylvinyl)phosphine,diphenyl(2-cyclohexylvinyl)phosphine,dicyclohexyl(2-cyclohexylvinyl)phosphine,dicyclopentyl(2-cyclohexylvinyl)phosphine,dipiperidyl(2-cyclohexylvinyl)phosphine,dipyrrolidyl(2-cyclohexylvinyl)phosphine,dipyridyl(2-cyclohexylvinyl)phosphine,dipyrryl(2-cyclohexylvinyl)phosphine, dimethyl(2-pyridylvinyl)phosphine,diethyl(2-pyridylvinyl)phosphine, di-n-propyl(2-pyridylvinyl)phosphine,di-t-butyl(2-pyridylvinyl)phosphine,di-n-octyl(2-pyridylvinyl)phosphine,di-n-dodecyl(2-pyridylvinyl)phosphine,diphenyl(2-pyridylvinyl)phosphine,dicyclohexyl(2-pyridylvinyl)phosphine,dicyclopentyl(2-pyridylvinyl)phosphine,dipiperidyl(2-pyridylvinyl)phosphine,dipyrrolidyl(2-pyridylvinyl)phosphine,dipyridyl(2-pyridylvinyl)phosphine, anddipyrryl(2-pyridylvinyl)phosphine.

Specific examples ofdihydrocarbyl(2-hydrocarbyl-1-hydrocarbylvinyl)phosphines includedimethyl(2-phenyl-1-methylvinyl)phosphine,diethyl(2-phenyl-1-methylvinyl)phosphine,di-n-propyl(2-phenyl-1-methylvinyl)phosphine,di-t-butyl(2-phenyl-1-methylvinyl)phosphine,di-n-octyl(2-phenyl-1-methylvinyl)phosphine,di-n-dodecyl(2-phenyl-1-methylvinyl)phosphine,diphenyl(2-phenyl-1-methylvinyl)phosphine,dicyclohexyl(2-phenyl-1-methylvinyl)phosphine,dicyclopentyl(2-phenyl-1-methylvinyl)phosphine,dipiperidyl(2-phenyl-1-methylvinyl)phosphine,dipyrrolidyl(2-phenyl-1-methylvinyl)phosphine,dipyridyl(2-phenyl-1-methylvinyl)phosphine,dipyrryl(2-phenyl-1-methylvinyl)phosphine,dimethyl(2-ethyl-1-ethylvinyl)phosphine,diethyl(2-ethyl-1-ethylvinyl)phosphine,di-n-propyl(2-ethyl-1-ethylvinyl)phosphine,di-t-butyl(2-ethyl-1-ethylvinyl)phosphine,di-n-octyl(2-ethyl-1-ethylvinyl)phosphine,di-n-dodecyl(2-ethyl-1-ethylvinyl)phosphine,diphenyl(2-ethyl-1-ethylvinyl)phosphine,dicyclohexyl(2-ethyl-1-ethylvinyl)phosphine,dicyclopentyl(2-ethyl-1-ethylvinyl)phosphine,dipiperidyl(2-ethyl-1-ethylvinyl)phosphine,dipyrrolidyl(2-ethyl-1-ethylvinyl)phosphine,dipyridyl(2-ethyl-1-ethylvinyl)phosphine,dipyrryl(2-ethyl-1-ethylvinyl)phosphine,dimethyl(2-cyclohexyl-1-propylvinyl)phosphine,diethyl(2-cyclohexyl-1-propylvinyl)phosphine,di-n-propyl(2-cyclohexyl-1-propylvinyl)phosphine,di-t-butyl(2-cyclohexyl-1-propylvinyl)phosphine,di-n-octyl(2-cyclohexyl-1-propylvinyl)phosphine,di-n-dodecyl(2-cyclohexyl-1-propylvinyl)phosphine,diphenyl(2-cyclohexyl-1-propylvinyl)phosphine,dicyclohexyl(2-cyclohexyl-1-propylvinyl)phosphine,dicyclopentyl(2-cyclohexyl-1-propylvinyl)phosphine,dipiperidyl(2-cyclohexyl-1-propylvinyl)phosphine,dipyrrolidyl(2-cyclohexyl-1-propylvinyl)phosphine,dipyridyl(2-cyclohexyl-1-propylvinyl)phosphine,dipyrryl(2,2-cyclohexyl-1-propylvinyl)phosphine,dimethyl(2-pyridyl-1-ethylvinyl)phosphine,diethyl(2-pyridyl-1-ethylvinyl)phosphine,di-n-propyl(2-pyridyl-1-ethylvinyl)phosphine,di-t-butyl(2-pyridyl-1-ethylvinyl)phosphine,di-n-octyl(2-pyridyl-1-ethylvinyl)phosphine,di-n-dodecyl(2-pyridyl-1-ethylvinyl)phosphine,diphenyl(2-pyridyl-1-ethylvinyl)phosphine,dicyclohexyl(2-pyridyl-1-ethylvinyl)phosphine,dicyclopentyl(2-pyridyl-1-ethylvinyl)phosphine,dipiperidyl(2-pyridyl-1-ethylvinyl)phosphine,dipyrrolidyl(2-pyridyl-1-ethylvinyl)phosphine,dipyridyl(2-pyridyl-1-ethylvinyl)phosphine, anddipyrryl(2-pyridyl-1-ethylvinyephosphine.

Specific examples of dihydrocarbyl(1-hydrocarbylvinyl)phosphines includedimethyl(1-methylvinyl)phosphine, diethyl(1-methylvinyl)phosphine,di-n-propyl (1-methylvinyl)phosphine,di-t-butyl(1-methylvinyl)phosphine, di-n-octyl(1-methylvinyl)phosphine,di-n-dodecyl(1-methylvinyl)phosphine, diphenyl(1-methylvinyl)phosphine,dicyclohexyl (1-methylvinyl)phosphine,dicyclopentyl(1-methylvinyl)phosphine,dipiperidyl(1-methylvinyl)phosphine,dipyrrolidyl(1-methylvinyl)phosphine, dipyridyl(1-methylvinyl)phosphine,dipyrryl(1-methylvinyl)phosphine, dimethyl(1-ethylvinyl)phosphine,diethyl(1-ethylvinyl)phosphine, di-n-propyl(1-ethylvinyl)phosphine,di-t-butyl(1-ethylvinyl)phosphine, di-n-octyl (1-ethylvinyl)phosphine,di-n-dodecyl(1-ethylvinyl)phosphine, diphenyl(1-ethylvinyl)phosphine,dicyclohexyl(1-ethylvinyl)phosphine,dicyclopentyl(1-ethylvinyl)phosphine,dipiperidyl(1-ethylvinyl)phosphine, dipyrrolidyl(1-ethylvinyl)phosphine,dipyridyl(1-ethylvinyl)phosphine, dipyrryl(1-ethylvinyl)phosphine,dimethyl(1-propylvinyl)phosphine, diethyl(1-propylvinyl)phosphine,di-n-propyl(1-propylvinyl)phosphine, di-t-butyl(1-propylvinyl)phosphine,di-n-octyl(1-propylvinyl)phosphine,di-n-dodecyl(1-propylvinyl)phosphine, diphenyl(1-propylvinyl)phosphine,dicyclohexyl(1-propylvinyl)phosphine,dicyclopentyl(1-propylvinyl)phosphine,dipiperidyl(1-propylvinyl)phosphine,dipyrrolidyl(1-propylvinyl)phosphine, dipyridyl(1-propylvinyl)phosphine,and dipyrryl(1-propylvinyl)phosphine.

Phosphorus-Containing Initiator

As indicated above, certain aspects of the invention include preparingpolymer and copolymer using a phosphorus-containing organometal compoundas an anionic initiator, which may also be referred to as aphosphorus-containing initiator. In one or more embodiments, thephosphorus-containing initiator may be prepared by reacting a vinylorganophosphine with an organometal compound.

Organometal

In one or more embodiments, the organometal may be defined by theformula M R⁷ _(n), where M is a metal, R⁷ is a monovalent organic group,and n is equivalent to the valence of the metal. In one or moreembodiments, the metal is a group I or group II metal. In particularembodiments, the metal is lithium.

Because organolithium compounds are generally recognized as useful inanionic polymerizations, embodiments of the present invention will bedescribed based upon organolithium compounds or phosphorus-containingorganolithium compounds with the understanding that the skilled personwill be able to readily extend these teachings to other useful metals.Thus, embodiments of the invention are directed towardphosphorus-containing organolithium compounds prepared by reacting anorganolithium compound with vinyl organophosphine.

Exemplary types of organolithium compounds include hydrocarbyl lithiumsand substituted hydrocarbyl lithiums such as, but not limited to,alkyllithiums, cycloalkyllithiums, substituted cycloalkyllithiums,alkenyllithiums, cycloalkenyllithiums, substituted cycloalkenyllithiums,aryllithiums, allyllithiums, substituted aryllithiums, aralkyllithiums,alkaryllithiums, and alkynylllithiums, with each group preferablycontaining from 1 carbon atom, or the appropriate minimum number ofcarbon atoms to form the group, up to 20 carbon atoms. These hydrocarbylgroups may contain heteroatoms such as, but not limited to, nitrogen,boron, oxygen, silicon, sulfur, and phosphorus atoms. Specific examplesof useful organolithium compounds include t-butyllithium,n-butyllithium, and isobutyllithium.

As suggested above, the phosphorus-containing organometal compound(e.g., phosphorus-containing organolithium compound) is formed byreacting an organolithium compound with a vinyl organophosphine. Theamount of organolithium compound reacted with the vinyl organophosphinemay be represented as a molar ratio of organolithium to vinylorganophosphine (Li/P). In one or more embodiments, the molar ratio oforganolithium to vinyl organophosphine (Li/P) may be from 0.1:1 to 20:1,in other embodiments from 0.5:1 to 10:1, and in other embodiments from0.9:1 to 1.5:1.

In one or more embodiments, the phosphorus-containing organolithiumcompound is pre-formed, which includes reacting the organolithium andthe vinyl organophosphine compound in the presence of little to nomonomer. In one or more embodiments, the reaction between theorganolithium and the vinyl organophosphine takes place in the presenceof less than 1 mole percent, in other embodiments less than 0.5 molepercent, and in other embodiments less than 0.1 mole percent monomer tovinyl organophosphine. In particular embodiments, thephosphorus-containing organometal compound is formed in the substantialabsence of monomer, which refers to that amount of monomer or less thatwill not have an appreciable impact on the formation of thephosphorus-containing organometal or its use in anionic polymerization.

In one or more embodiments, the reaction between the organolithium andthe vinyl organophosphine compound takes place within a solvent. In oneor more embodiments, the solvent may be employed to either dissolve orsuspend one or more of the organolithium, the vinyl organophosphine, orthe phosphorus-containing organometal compound. Suitable solventsinclude those organic compounds that will not undergo polymerization orincorporation into a propagating polymer chain during polymerization ofmonomer in the presence of the phosphorus-containing organometalcompound. In one or more embodiments, these organic solvents are liquidat ambient temperature and pressure. Exemplary organic solvents includehydrocarbons with a low or relatively low boiling point such as aromatichydrocarbons, aliphatic hydrocarbons, and cycloaliphatic hydrocarbons.Non-limiting examples of aromatic hydrocarbons include benzene, toluene,xylenes, ethylbenzene, diethylbenzene, and mesitylene. Non-limitingexamples of aliphatic hydrocarbons include n-pentane, n-hexane,n-heptane, n-octane, n-nonane, n-decane, isopentane, isohexanes,isopentanes, isooctanes, 2,2-dimethylbutane, petroleum ether, kerosene,and petroleum spirits. And, non-limiting examples of cycloaliphatichydrocarbons include cyclopentane, cyclohexane, methylcyclopentane, andmethylcyclohexane. Mixtures of the above hydrocarbons may also be used.The low-boiling hydrocarbon solvents are typically separated from thepolymer upon completion of the polymerization. Other examples of organicsolvents include high-boiling hydrocarbons of high molecular weights,such as paraffinic oil, aromatic oil, or other hydrocarbon oils that arecommonly used to oil-extend polymers. Since these hydrocarbons arenon-volatile, they typically do not require separation and remainincorporated in the polymer. In yet other embodiments, examples ofuseful organic solvents include non-Zerwittenoff polar organic solvents.These solvents include, but are not limited to, ethers, such as dimethylether and diethyl ether, as well as cyclic ethers, such astetrahydrofuran (THF) and 2,2-bis(2′-tetrahydrofuryl)propane. Othernon-Zerwittenoff polar organic solvents include tertiary amines such astri-n-butyl amine.

In one or more embodiments, the pre-formed solution concentration of theorganolithium compound, the vinyl organophosphine compound, and/or thephosphorus-containing organometal compound within the solvent may befrom about 5 M (molar) to about 0.005 M, in other embodiments from about2 M to about 0.05 M, and in other embodiments from about 1.1 M to about0.075 M.

In one or more embodiments, the reaction between the organolithium andthe vinyl organophosphine compound may be conducted at a temperaturefrom about −78° C. to about 100° C., in other embodiments from about 0°C. to about 75° C., and in other embodiments from about 10° C. to about50° C. Also, this reaction can be conducted at atmospheric pressure. Inone or more embodiments, the reaction is conducted under anaerobicconditions.

In one or more embodiments, the reaction between the organolithium andthe vinyl organophosphine compound may take place in the presence of apolar coordinator. Compounds useful as polar coordinators include thosecompounds having an oxygen or nitrogen heteroatom and a non-bonded pairof electrons. Examples of useful polar coordinators include linear andcyclic oligomeric oxolanyl alkanes; dialkyl ethers of mono and oligoalkylene glycols (also known as glyme ethers); “crown” ethers; tertiaryamines; linear THF oligomers; and the like. Linear and cyclic oligomericoxolanyl alkanes are described in U.S. Pat. No. 4,429,091, which isincorporated herein by reference. Specific examples of compounds usefulas polar coordinators include 2,2-bis(2′-tetrahydrofuryl)propane,1,2-dimethoxyethane, N,N,N′,N′-tetramethylethylenediamine (TMEDA),tetrahydrofuran (THF), 1,2-dipiperidylethane, dipiperidylmethane,hexamethylphosphoramide, N—N′-dimethylpiperazine, diazabicyclooctane,dimethyl ether, diethyl ether, tri-n-butylamine, and mixtures thereof.When employed, the amount of polar coordinator present during thereaction between the organolithium and the vinyl organophosphine may befrom about 10,000 to about 0.001, in other embodiments from about 100 toabout 0.05, and in other embodiments from about 50 to about 0.1 molesper mole of the vinyl organophosphine.

Initiator Structure

While the vinyl organophosphine and the organometal are believed toreact to form the phosphorus-containing organometal initiator, the exactchemical structure resulting from the reaction between all species isnot known with a great deal of certainty. For example, the structure ofthe phosphorus-containing organometal initiators may depend on stabilityof the anion formed by a reaction with the organometal compound.

Without wishing to be bound by any particular theory, it is believedthat in one or more embodiments, vinyldihydrocarbyl phosphines react toform phosphorus-containing organolithium compounds that can be definedby the formula II:

where M is a metal, R¹ and R² are each independently monovalent organicgroups, or where R¹ and R² join to form a divalent organic group, whereR³, R⁴, and R⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group, andwhere R⁶ is a bond or a divalent organic group. In particularembodiments, R³, R⁴, and R⁵ are hydrogen atoms. In these or otherparticular embodiments, M is a group I (e.g. lithium) or group II (e.g.magnesium) metal. In these or other particular embodiments, R⁶ is adivalent organic group defined by the formula III:

where R¹, R², R³, R⁴, and R⁵ are defined as above, and x is an integerfrom 1 to 19. In particular embodiments, x is an integer from 1 to 10,and in other embodiments from 1 to 6. It is believed that molecules ofthe Formula II are obtained when, for example, butyl lithium is reactedwith vinyl diphenyl phosphine.

With respect to Formula II, where R⁶ is a substituent according toFormula III, it is believed that the alpha carbon of Formula III (i.e.,the carbon next to the phosphorus atom) will be bonded to the metal atom(i.e., M) of Formula II, and the beta carbon of Formula III (i.e., thesecond carbon atom from the phosphorus atom) will be bonded to the alphacarbon of Formula II.

Again, without wishing to be bound by any particular theory, it isbelieved that certain substituted vinyl organophosphines, such asdihydrocarbyl(2-dihydrocarbylvinyl)phosphines, react to formphosphorus-containing organolithium compounds that can be defined by theformula IV:

where M is a metal, R¹ and R² are each independently monovalent organicgroups, or where R¹ and R² join to form a divalent organic group, whereR³, R⁴, and R⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group, andwhere R⁶ is a bond or a divalent organic group. In particularembodiments, R³, R⁴, and R⁵ are hydrocarbyl groups. In these or otherparticular embodiments, M is a group I (e.g. lithium) or group II (e.g.magnesium) metal.

In these or other particular embodiments, R⁶ may be a divalent organicgroup defined by the Formula III. With respect to Formula IV, where R⁶is a substituent according to Formula III, it is believed that the betacarbon of Formula III will be bonded to the metal atom of Formula IV,and the alpha carbon of Formula III will be bonded to the beta carbon ofFormula IV.

In one or more embodiments, a solvent may be employed as a carrier toeither dissolve or suspend the initiator in order to facilitate thedelivery of the initiator to the polymerization system. In otherembodiments, monomer can be used as the carrier. In yet otherembodiments, the initiator can be used in their neat state without anysolvent.

In one or more embodiments, suitable solvents include those organiccompounds that will not undergo polymerization or incorporation intopropagating polymer chains during the polymerization of monomer in thepresence of the catalyst or initiator. In one or more embodiments, theseorganic species are liquid at ambient temperature and pressure. In oneor more embodiments, these organic solvents are inert to the catalyst orinitiator. Exemplary organic solvents include hydrocarbons with a low orrelatively low boiling point such as aromatic hydrocarbons, aliphatichydrocarbons, and cycloaliphatic hydrocarbons. Non-limiting examples ofaromatic hydrocarbons include benzene, toluene, xylenes, ethylbenzene,diethylbenzene, and mesitylene. Non-limiting examples of aliphatichydrocarbons include n-pentane, n-hexane, n-heptane, n-octane, n-nonane,n-decane, isopentane, isohexanes, isopentanes, isooctanes,2,2-dimethylbutane, petroleum ether, kerosene, and petroleum spirits.And, non-limiting examples of cycloaliphatic hydrocarbons includecyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane.Mixtures of the above hydrocarbons may also be used. As is known in theart, aliphatic and cycloaliphatic hydrocarbons may be desirably employedfor environmental reasons. The low-boiling hydrocarbon solvents aretypically separated from the polymer upon completion of thepolymerization.

Other examples of organic solvents include high-boiling hydrocarbons ofhigh molecular weights, including hydrocarbon oils that are commonlyused to oil-extend polymers. Examples of these oils include paraffinicoils, aromatic oils, naphthenic oils, vegetable oils other than castoroils, and low PCA oils including MES, TDAE, SRAE, heavy naphthenic oils.Since these hydrocarbons are non-volatile, they typically do not requireseparation and remain incorporated in the polymer.

In one or more embodiments, stabilized solutions of thephosphorus-containing organometal initiator of this invention can beprepared by chain extending the initiator compound. The technique ofchain extending anionic polymerization initiators is known in the art asdescribed in U.S. Publication No. 2011/0112263 and U.S. ProvisionalApplication Ser. No. 61/576,043, which are incorporated herein byreference. In general, this technique includes polymerizing a limitedamount of monomer (e.g., 3 to 25 units of butadiene) to form astabilized chain-extended initiator. These chain-extended initiators canbe represented by the formulas II and IV above, where R⁶ includes adivalent oligomeric substituent formed by the polymerization of thelimited amount of monomer (i.e., 3 to 25 mer units).

Polymerization Process

In one or more embodiments, polydiene or diene copolymers, the latter ofwhich may also be referred to as polydiene copolymers, are prepared byintroducing the pre-formed phosphorus-containing organometal compoundwith monomer to be polymerized. It is believed that the polymerizationproceeds by anionic polymerization of the monomer with thephosphorus-containing organometal compound serving as the initiator. Aswill be described in more detail below, the polymer, which includes aphosphorus-containing functional group at the head of the polymer chain,may be end-functionalized to produce a polymer having a functional groupat the tail-end of the polymer (i.e., a telechelic polymer is produced).

In one or more embodiments, the monomer to be polymerized with thephosphorus-containing organometal includes conjugated diene monomer andoptionally monomer copolymerizable therewith. Examples of conjugateddiene monomer include 1,3-butadiene, isoprene, 1,3-pentadiene,1,3-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene,2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, and 2,4-hexadiene. Mixtures of two or moreconjugated dienes may also be utilized in copolymerization. Examples ofmonomer copolymerizable with conjugated diene monomer includevinyl-substituted aromatic compounds such as styrene, p-methylstyrene,α-methylstyrene, and vinyl naphthalene.

It is believed that use of the phosphorus-containing initiator producespolymers by anionic polymerization techniques or mechanisms. The keymechanistic features of anionic polymerization have been described inbooks (e.g., Hsieh, H. L.; Quirk, R. P. Anionic Polymerization:Principles and Practical Applications; Marcel Dekker: New York, 1996)and review articles (e.g., Hadjichristidis, N.; Pitsikalis, M.; Pispas,S.; Iatrou, H.; Chem. Rev. 2001, 101(12), 3747-3792). These initiatorsmay advantageously produce living polymers that, prior to quenching, arecapable of reacting with additional monomers for further chain growth orreacting with certain coupling and/or functionalizing agents to givecoupled or terminal-functionalized polymers. As those skilled in the artappreciate, these reactive polymers include a reactive chain end, whichis believed to be ionic, at which a reaction between a functionalizingand/or coupling agent and the polymer takes place.

Anionic polymerization may be conducted in polar solvents, non-polarsolvents, and mixtures thereof. In one or more embodiments, a solventmay be employed as a carrier to either dissolve or suspend the initiatorin order to facilitate the delivery of the initiator to thepolymerization system. Solvents useful for conducting thepolymerizations include those solvents mentioned above that are usefulin preparing the initiator solutions. In particular embodiments, alkanesand/or cycloalkanes are employed.

In order to promote the randomization of comonomers in copolymerizationand to control the microstructure (such as 1,2-linkage of conjugateddiene monomer) of the polymer, a randomizer, which is typically a polarcoordinator, may be employed along with the anionic initiator. Compoundsuseful as randomizers include those having an oxygen or nitrogenheteroatom and a non-bonded pair of electrons. Exemplary types ofrandomizers include linear and cyclic oligomeric oxolanyl alkanes;dialkyl ethers of mono and oligo alkylene glycols (also known as glymeethers); crown ethers; tertiary amines; linear THF oligomers; alkalimetal alkoxides; and alkali metal sulfonates. Linear and cyclicoligomeric oxolanyl alkanes are described in U.S. Pat. No. 4,429,091,which is incorporated herein by reference. Specific examples ofrandomizers include 2,2-bis(2′-tetrahydrofuryl)propane,1,2-dimethoxyethane, N,N,N′,N′-tetramethylethylenediamine (TMEDA),tetrahydrofuran (THF), 1,2-dipiperidylethane, dipiperidylmethane,hexamethylphosphoramide, N,N′-dimethylpiperazine, diazabicyclooctane,dimethyl ether, diethyl ether, tri-n-butylamine, potassium t-amylate,potassium 4-dodecylsulfonate, and mixtures thereof.

When preparing elastomeric copolymers, such as those containingconjugated diene monomers and vinyl-substituted aromatic monomers, theconjugated diene monomers and vinyl-substituted aromatic monomers may beused at a ratio of 95:5 to 50:50, or in other embodiments, 95:5 to65:35. In order to promote the randomization of comonomers incopolymerization and to control the microstructure (such as 1,2-linkageof conjugated diene monomer) of the polymer, a randomizer, which istypically a polar coordinator, may be employed along with the anionicinitiator. Compounds useful as randomizers include those polarcoordinators mentioned above. In other embodiments, useful randomizersinclude potassium alkoxides.

The amount of randomizer to be employed may depend on various factorssuch as the desired microstructure of the polymer, the ratio of monomerto comonomer, the polymerization temperature, as well as the nature ofthe specific randomizer employed. In one or more embodiments, the amountof randomizer employed may range between 0.05 and 100 moles per mole ofthe anionic initiator. In one or more embodiments, the amount ofrandomizer employed includes that amount introduced during formation ofthe initiator (i.e., the lithium organophosphide). In other embodiments,additional randomizer is added to the monomer to be polymerized.

The anionic initiator and the randomizer can be introduced to thepolymerization system by various methods. In one or more embodiments,the anionic initiator and the randomizer may be added separately to themonomer to be polymerized in either a stepwise or simultaneous manner.In other embodiments, the anionic initiator and the randomizer may bepre-mixed outside the polymerization system either in the absence of anymonomer or in the presence of a small amount of monomer, and theresulting mixture may be aged, if desired, and then added to the monomerthat is to be polymerized.

Production of the reactive polymer can be accomplished by polymerizingconjugated diene monomer, optionally together with monomercopolymerizable with conjugated diene monomer, in the presence of aneffective amount of the initiator (i.e., the amount ofphosphorus-containing organolithium compound). The introduction of theinitiator, the conjugated diene monomer, optionally the comonomer, andany solvent if employed forms a polymerization mixture in which thereactive polymer is formed. The amount of the initiator to be employedmay depend on the interplay of various factors such as the type ofinitiator employed, the purity of the ingredients, the polymerizationtemperature, the polymerization rate and conversion desired, themolecular weight desired, and many other factors.

In one or more embodiments, the initiator loading (i.e., the amount ofphosphorus-containing organolithium compound) may be varied from about0.05 to about 100 mmol, in other embodiments from about 0.1 to about 50mmol, and in still other embodiments from about 0.2 to about 5 mmol per100 gram of monomer.

Polymerization System

In one or more embodiments, the polymerization may be carried out in apolymerization system that includes a substantial amount of solvent. Inone embodiment, a solution polymerization system may be employed inwhich both the monomer to be polymerized and the polymer formed aresoluble in the solvent. In another embodiment, a precipitationpolymerization system may be employed by choosing a solvent in which thepolymer formed is insoluble. In both cases, an amount of solvent inaddition to the amount of solvent that may be used in preparing thecatalyst or initiator is usually added to the polymerization system. Theadditional solvent may be the same as or different from the solvent usedin preparing the catalyst or initiator. Exemplary solvents have been setforth above. In one or more embodiments, the solvent content of thepolymerization mixture may be more than 20% by weight, in otherembodiments more than 50% by weight, and in still other embodiments morethan 80% by weight based on the total weight of the polymerizationmixture.

The polymerization may be conducted in any conventional polymerizationvessels known in the art. In one or more embodiments, solutionpolymerization can be conducted in a conventional stirred-tank reactor.In other embodiments, bulk polymerization can be conducted in aconventional stirred-tank reactor, especially if the monomer conversionis less than about 60%. In still other embodiments, the polymerizationmay be conducted in an elongated reactor in which the viscous cementunder polymerization is driven to move by piston, or substantially bypiston. For example, extruders in which the cement is pushed along by aself-cleaning single-screw or double-screw agitator are suitable forthis purpose.

In one or more embodiments, all of the ingredients used for thepolymerization can be combined within a single vessel (e.g., aconventional stirred-tank reactor), and all steps of the polymerizationprocess can be conducted within this vessel. In other embodiments, twoor more of the ingredients can be pre-combined in one vessel and thentransferred to another vessel where the polymerization of monomer (or atleast a major portion thereof) may be conducted.

The polymerization can be carried out as a batch process, a semi-batchprocess a continuous process, or a semi-continuous process. In thesemi-continuous process, the monomer is intermittently charged as neededto replace that monomer already polymerized. In one or more embodiments,the conditions under which the polymerization proceeds may be controlledto maintain the temperature of the polymerization mixture within a rangefrom about −10° C. to about 200° C., in other embodiments from about 0°C. to about 150° C., and in other embodiments from about 20° C. to about100° C. In one or more embodiments, the heat of polymerization may beremoved by external cooling by a thermally controlled reactor jacket,internal cooling by evaporation and condensation of the monomer throughthe use of a reflux condenser connected to the reactor, or a combinationof the two methods. Also, the polymerization conditions may becontrolled to conduct the polymerization under a pressure of from about0.1 atmosphere to about 50 atmospheres, in other embodiments from about0.5 atmosphere to about 20 atmosphere, and in other embodiments fromabout 1 atmosphere to about 10 atmospheres. In one or more embodiments,the pressures at which the polymerization may be carried out includethose that ensure that the majority of the monomer is in the liquidphase. In these or other embodiments, the polymerization mixture may bemaintained under anaerobic conditions.

Additional Terminal Functionalization

In one or more embodiments, the polymers and copolymers produced usingthe anionic polymerization initiators according the present invention(e.g., the phosphorus-containing initiator) may have a reactive orliving end. In one or more embodiments, at least about 30% of thepolymer molecules contain living ends, in other embodiments at leastabout 50% of the polymer molecules contain living ends, and in otherembodiments at least about 80% contain living ends.

These reactive polymers, which may also be referred to as livingpolymers, can be protonated or subsequently functionalized or coupled.Protonation can occur by the addition of any compound that can donate aproton to the living end. Examples include water, isopropyl alcohol, andmethyl alcohol.

In one or more embodiments, the living or reactive polymer can beterminated with a compound that will impart a functional group to theterminus of the polymer. Useful functionalizing agents include thoseconventionally employed in the art. Types of compounds that have beenused to end-functionalize living polymers include carbon dioxide,benzophenones, benzaldehydes, imidazolidones, pyrrolidinones,carbodiimides, ureas, isocyanates, and Schiff bases including thosedisclosed in U.S. Pat. Nos. 3,109,871, 3,135,716, 5,332,810, 5,109,907,5,210,145, 5,227,431, 5,329,005, 5,935,893, which are incorporatedherein by reference. Specific examples include trialkyltin halides suchas triisobutyltin chloride, as disclosed in U.S. Pat. Nos. 4,519,431,4,540,744, 4,603,722, 5,248,722, 5,349,024, 5,502,129, and 5,877,336,which are incorporated herein by reference. Other examples includecyclic amino compounds such as hexamethyleneimine alkyl chloride, asdisclosed in U.S. Pat. Nos. 5,786,441, 5,916,976 and 5,552,473, whichare incorporated herein by reference. Other examples includeN-substituted aminoketones, N-substituted thioaminoketones,N-substituted aminoaldehydes, and N-substituted thioaminoaldehydes,including N-methyl-2-pyrrolidone or dimethylimidazolidinone (i.e.,1,3-dimethylethyleneurea) as disclosed in U.S. Pat. Nos. 4,677,165,5,219,942, 5,902,856, 4,616,069, 4,929,679, 5,115,035, and 6,359,167,which are incorporated herein by reference. Additional examples includecyclic sulfur-containing or oxygen containing azaheterocycles such asdisclosed in WO 2004/020475, U.S. Publication No. 2006/0178467 and U.S.Pat. No. 6,596,798, which are incorporated herein by reference. Otherexamples include boron-containing terminators such as disclosed in U.S.Pat. No. 7,598,322, which is incorporated herein by reference. Stillother examples include cyclic siloxanes such ashexamethylcyclotrisiloxane, including those disclosed in copending U.S.Ser. No. 60/622,188, which is incorporated herein by reference. Further,other examples include α-halo-ω-amino alkanes, such as1-(3-bromopropyl)-2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopentane,including those disclosed in copending U.S. Ser. Nos. 60/624,347 and60/643,653, which are incorporated herein by reference. Yet otherexamples include silane-type terminators, such as3-(1,3-dimethylbutylidene)aminopropyl-triethoxysilane. Still otherexamples include benzaldehyde-type terminators, such as3,4-di(tert-butyldimethylsiloxy)benzaldehyde, which are disclosed inU.S. Publication No. 2010/0286348, which is incorporated herein byreference.

In one or more embodiments, the living polymer can be coupled to linktwo or more living polymer chains together. In certain embodiments, theliving polymer can be treated with both coupling and functionalizingagents, which serve to couple some chains and functionalize otherchains. The combination of coupling agent and functionalizing agent canbe used at various molar ratios. Although the terms coupling andfunctionalizing agents have been employed in this specification, thoseskilled in the art appreciate that certain compounds may serve bothfunctions. That is, certain compounds may both couple and provide thepolymer chains with a functional group. Those skilled in the art alsoappreciate that the ability to couple polymer chains may depend upon theamount of coupling agent reacted with the polymer chains. For example,advantageous coupling may be achieved where the coupling agent is addedin a one to one ratio between the equivalents of lithium on theinitiator and equivalents of leaving groups (e.g., halogen atoms) on thecoupling agent.

Exemplary coupling agents include metal halides, metalloid halides,alkoxysilanes, and alkoxystannanes.

In one or more embodiments, useful metal halides or metalloid halidesmay be selected from the group comprising compounds expressed by theformula (1) R¹ _(n)M_(4-n), the formula (2) M¹X₄, and the formula (3)M²X₃, where R¹ is the same or different and represents a monovalentorganic group with carbon number of 1 to about 20, M¹ in the formulas(1) and (2) represents a tin atom, silicon atom, or germanium atom, M²represents a phosphorus atom, X represents a halogen atom, and nrepresents an integer of 0-3.

Exemplary compounds expressed by the formula (1) include halogenatedorganic metal compounds, and the compounds expressed by the formulas (2)and (3) include halogenated metal compounds.

In the case where M¹ represents a tin atom, the compounds expressed bythe formula (1) can be, for example, triphenyltin chloride, tributyltinchloride, triisopropyltin chloride, trihexyltin chloride, trioctyltinchloride, diphenyltin dichloride, dibutyltin dichloride, dihexyltindichloride, dioctyltin dichloride, phenyltin trichloride, butyltintrichloride, octyltin trichloride and the like. Furthermore, tintetrachloride, tin tetrabromide and the like can be exemplified as thecompounds expressed by formula (2).

In the case where M¹ represents a silicon atom, the compounds expressedby the formula (1) can be, for example, triphenylchlorosilane,trihexylchlorosilane, trioctylchlorosilane, tributylchlorosilane,trimethylchlorosilane, diphenyldichlorosilane, dihexyldichlorosilane,dioctyldichlorosilane, dibutyldichlorosilane, dimethyldichlorosilane,methyltrichlorosilane, phenyltrichlorosilane, hexyltrichlorosilane,octyltrichlorosilane, butyltrichlorosilane, methyltrichlorosilane andthe like. Furthermore, silicon tetrachloride, silicon tetrabromide andthe like can be exemplified as the compounds expressed by the formula(2). In the case where M¹ represents a germanium atom, the compoundsexpressed by the formula (1) can be, for example, triphenylgermaniumchloride, dibutylgermanium dichloride, diphenylgermanium dichloride,butylgermanium trichloride and the like. Furthermore, germaniumtetrachloride, germanium tetrabromide and the like can be exemplified asthe compounds expressed by the formula (2). Phosphorus trichloride,phosphorus tribromide and the like can be exemplified as the compoundsexpressed by the formula (3). In one or more embodiments, mixtures ofmetal halides and/or metalloid halides can be used.

In one or more embodiments, useful alkoxysilanes or alkoxystannanes maybe selected from the group comprising compounds expressed by the formula(1) R¹ _(n)M¹(OR)_(4-n), where R¹ is the same or different andrepresents a monovalent organic group with carbon number of 1 to about20, M¹ represents a tin atom, silicon atom, or germanium atom, ORrepresents an alkoxy group where R represents a monovalent organicgroup, and n represents an integer of 0-3.

Exemplary compounds expressed by the formula (4) include tetraethylorthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate,tetraethoxy tin, tetramethoxy tin, and tetrapropoxy tin.

In one embodiment, the functionalizing agent may be added to the livingpolymer cement (i.e., polymer and solvent) once a peak polymerizationtemperature, which is indicative of nearly complete monomer conversion,is observed. Because live ends may self-terminate, the functionalizingagent should be added within about 25 to 35 minutes of the peakpolymerization temperature.

In one or more embodiments, the amount of the functionalizing agentemployed can be described with reference to the amount of metal cationassociated with the initiator. For example, the molar ratio of thefunctionalizing agent to the lithium metal may be from about 0.1:1 toabout 2:1, in other embodiments from about 0.3:1 to about 2:1, in otherembodiments from about 0.6:1 to about 1.5:1, and in other embodimentsfrom 0.8:1 to about 1.2:1.

In one or more embodiments, the functionalizing agent may be introducedto the polymerization mixture as a solution within an organic solvent.Suitable solvents include those described herein including those used toprepare the polymerization mixture. In certain embodiments, the samesolvent employed to prepare the polymerization mixture can be used toprepare the solution of the functionalizing agent. Advantageously, oneor more functionalizing agent of the present invention formtechnologically useful and stable solutions in aliphatic solvents suchas hexane, cyclohexane, and/or derivatives thereof. In one or moreembodiments, the concentration of the functionalizing agent in aliphaticsolvent may be at least 0.05 molar, in other embodiments at least 0.5molar, in other embodiments at least 1 molar and in other embodimentsfrom about 0.5 to about 3 molar.

In one or more embodiments, the functionalizing agent can be reactedwith the reactive polymer after a desired monomer conversion is achievedbut before the polymerization mixture is quenched by a quenching agent.In one or more embodiments, the reaction between the functionalizingagent and the reactive polymer may take place within 180 minutes, inother embodiments within 60 minutes, in other embodiments within 30minutes, in other embodiments within 5 minutes, and in other embodimentswithin one minute after the peak polymerization temperature is reached.In one or more embodiments, the reaction between the functionalizingagent and the reactive polymer can occur once the peak polymerizationtemperature is reached. In other embodiments, the reaction between thefunctionalizing agent and the reactive polymer can occur after thereactive polymer has been stored. In one or more embodiments, thestorage of the reactive polymer occurs at room temperature or belowunder an inert atmosphere. In one or more embodiments, the reactionbetween the functionalizing agent and the reactive polymer may takeplace at a temperature from about 10° C. to about 150° C., and in otherembodiments from about 20° C. to about 100° C. The time required forcompleting the reaction between the functionalizing agent and thereactive polymer depends on various factors such as the type and amountof the initiator used to prepare the reactive polymer, the type andamount of the functionalizing agent, as well as the temperature at whichthe functionalization reaction is conducted. In one or more embodiments,the reaction between the functionalizing agent and the reactive polymercan be conducted for about 10 to 60 minutes.

The amount of the functionalizing agent that can be reacted with thereactive polymer may depend on various factors including the type andamount of initiator used to initiate the polymerization and the desireddegree of functionalization. In one or more embodiments, the amount ofthe functionalizing agent employed can be described with reference tothe amount of metal cation associated with the initiator. For example,the molar ratio of the functionalizing agent to the lithium metal may befrom about 0.1:1 to about 2:1, in other embodiments from about 0.3:1 toabout 2:1, in other embodiments from about 0.6:1 to about 1.5:1, and inother embodiments from 0.8:1 to about 1.2:1.

In one or more embodiments, the functionalizing agent may be introducedto the polymerization mixture as a solution within an organic solvent.Suitable solvents include those described herein including those used toprepare the polymerization mixture. In certain embodiments, the samesolvent employed to prepare the polymerization mixture can be used toprepare the solution of the functionalizing agent. Advantageously, oneor more functionalizing agent of the present invention formtechnologically useful and stable solutions in aliphatic solvents suchas hexane, cyclohexane, and/or derivatives thereof. In one or moreembodiments, the concentration of the functionalizing agent in aliphaticsolvent may be at least 0.05 molar, in other embodiments at least 0.5molar, in other embodiments at least 1 molar and in other embodimentsfrom about 0.5 to about 3 molar.

Quenching

In one or more embodiments, in lieu of or after the reaction between thereactive polymer and the functionalizing agent has been accomplished orcompleted, a quenching agent can be added to the polymerization mixturein order to inactivate any residual reactive polymer chains and/or theinitiator. The quenching agent may include a protic compound, whichincludes, but is not limited to, an alcohol, a carboxylic acid, aninorganic acid, water, or a mixture thereof. An antioxidant such as2,6-di-tert-butyl-4-methylphenol may be added along with, before, orafter the addition of the quenching agent. The amount of the antioxidantemployed may be in the range of 0.2% to 1% by weight of the polymerproduct.

Polymer Isolation

When the polymerization mixture has been quenched, the polymer productcan be recovered from the polymerization mixture by using anyconventional procedures of desolventization and drying that are known inthe art. For instance, the polymer can be recovered by subjecting thepolymer cement to steam desolventization, followed by drying theresulting polymer crumbs in a hot air tunnel. Alternatively, the polymermay be recovered by directly drying the polymer cement on a drum dryer.The content of the volatile substances in the dried polymer can be below1%, and in other embodiments below 0.5% by weight of the polymer.

Polymer Product

While the use of the phosphorus-containing initiator, optionally with acoupling agent and/or functionalizing agent, are believed to react toproduce novel functionalized polymers, the exact chemical structure ofthe functionalized polymer produced in every embodiment is not knownwith any great degree of certainty, particularly as the structurerelates to the residue imparted to the polymer chain end by thefunctionalizing agent. Indeed, it is speculated that the structure ofthe functionalized polymer may depend upon various factors such as theconditions employed to prepare the reactive polymer (e.g., the type andamount of the initiator) and the conditions employed to react thefunctionalizing agent with the reactive polymer.

In one or more embodiments, practice of the present inventionadvantageously produces polymer having a relatively high percentage ofphosphorus-containing groups located at the head of the polymer chain.Thus, while the prior art contemplates the use of lithium dialkylphosphides as initiators, practice of the present inventionadvantageously yields an unexpectedly higher number of polymer chainshaving a phosphorus-containing head group. Moreover, this isadvantageously achieved at technologically useful polymerizationconditions and rates, which generally include temperatures in excess of25° C., in other embodiments in excess of 30° C., and in otherembodiments in excess of 50° C. In one or more embodiments, the polymerproduced according to the present invention includes at least 30%, inother embodiments at least 50%, and in other embodiments at least 60%polymer having a phosphorus-containing head group.

In one or more embodiments, polymers produced according to embodimentsof the present invention may include a functionalized polymer defined bythe formula V:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group. In the case where ω is a coupling group, ωmay have a functionality of 2 or more (e.g., 3 or 4) whereby 2 or morepolymer chains (i.e., π) extend from the coupling group.

In other embodiments, polymers produced according to the presentinvention may include a functionalized polymer defined by the formulaVI:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group. In the case where ω is a coupling group, ωmay have a functionality of 2 or more (e.g., 3 or 4) whereby 2 or morepolymer chains (i.e., π) extend from the coupling group.

In one or more embodiments, the polymer chain (π) of the functionalizedpolymer contains unsaturation. In these or other embodiments, thepolymer chain is vulcanizable. The polymer chain can have a glasstransition temperature (T_(g)) that is less than 0° C., in otherembodiments less than −20° C., and in other embodiments less than −30°C. In one embodiment, the polymer chain may exhibit a single glasstransition temperature.

In one or more embodiments, the polymer chain (π) prepared according tothis invention may be medium or low cis polydienes (or polydienecopolymers) including those prepared by anionic polymerizationtechniques. These polydienes can have a cis content of from about 10% to60%, in other embodiments from about 15% to 55%, and in otherembodiments from about 20% to about 50%, where the percentages are basedupon the number of diene mer units in the cis configuration versus thetotal number of diene mer units. These polydienes may also have a1,2-linkage content (i.e. vinyl content) from about 10% to about 90%, inother embodiments from about 10% to about 60%, in other embodiments fromabout 15% to about 50%, and in other embodiments from about 20% to about45%, where the percentages are based upon the number of diene mer unitsin the vinyl configuration versus the total number of diene mer units.The balance of the diene units may be in the trans-1,4-linkageconfiguration.

In particular embodiments, the polymer chain (π) may be a copolymer ofbutadiene, styrene, and optionally isoprene. These may include randomcopolymers. In other embodiments, the polymers are block copolymers ofpolybutadiene, polystyrene, and optionally polyisoprene. In particularembodiments, the polymers are hydrogenated or partially hydrogenated. Inone or more embodiments, the polymer chain (π) is a copolymer of styreneand conjugated diene where the molar ratio of styrene mer units toconjugated diene mer units is from about 1:1 to about 0.05:1, in otherembodiments from about 0.7:1 to about 0.1:1, and in other embodimentsfrom about 0.5:1 to about 0.2:1.

In one or more embodiments, the polymer chain π is ananionically-polymerized polymer selected from the group consisting ofpolybutadiene, polyisoprene, poly(styrene-co-butadiene),polystyrene-co-butadiene-co-isoprene), poly(isoprene-co-styrene), andpoly(butadiene-co-isoprene). The number average molecular weight (M_(n))of these polymers may be from about 1,000 to about 1,000,000, in otherembodiments from about 5,000 to about 1,000,000, in other embodimentsfrom about 50,000 to about 500,000, and in other embodiments from about100,000 to about 300,000, as determined by using gel permeationchromatography (GPC) calibrated with polystyrene standards andMark-Houwink constants for the polymer in question. The polydispersity(M_(w)/M_(n)) of these polymers may be from about 1.0 to about 3.0, andin other embodiments from about 1.1 to about 2.0.

In particular embodiments, the polymers of this invention are copolymersof 1,3-butadiene, styrene, and optionally isoprene. These may includerandom copolymers and block copolymers. In one or more embodiments, therandom polydiene copolymers may include from about 10 to about 50% byweight, in other embodiments from about 15 to about 40% by weight, andin other embodiments from about 20 to about 30% by weight units derivingfrom styrene, with the balance including units deriving from conjugateddiene monomer, such as 1,3-butadiene, having low or medium cis contentas described above.

In particular embodiments, the functional group located at the chain end(i.e., ω) can react or interact with reinforcing filler to reduce the50° C. hysteresis loss of vulcanizates prepared there from.

Copolymerization with Vinyl Organophosphines

As indicated above, other aspects of the present invention are directedtoward copolymers prepared by anionically polymerizing vinylorganophosphines with diene monomer, optionally together with polymercopolymerizable therewith. Conjugated diene monomer, as well as monomercopolymerizable therewith (e.g., styrene), are described above. Also,anionic polymerization techniques are described above.

The practice of these embodiments is not limited by the selection of anyparticular anionic initiators. In one or more embodiments, the anionicinitiator employed is a functional initiator that imparts a functionalgroup at the head of the polymer chain (i.e., the location from whichthe polymer chain is started). In particular embodiments, the functionalgroup includes one or more heteroatoms (e.g., nitrogen, oxygen, boron,silicon, sulfur, tin, and phosphorus atoms) or heterocyclic groups. Incertain embodiments, the functional group reduces the 50° C. hysteresisloss of carbon-black filled vulcanizates prepared from polymerscontaining the functional group as compared to similar carbon-blackfilled vulcanizates prepared from polymer that does not include thefunctional group. In certain embodiments, the initiator employed mayinclude the phosphorus-containing initiator described above.

Exemplary anionic initiators include organolithium compounds. In one ormore embodiments, organolithium compounds may include heteroatoms. Inthese or other embodiments, organolithium compounds may include one ormore heterocyclic groups.

Types of organolithium compounds include alkyllithium, aryllithiumcompounds, and cycloalkyllithium compounds. Specific examples oforganolithium compounds include ethyllithium, n-propyllithium,isopropyllithium, n-butyllithium, sec-butyllithium, t-butyllithium,n-amyllithium, isoamyllithium, and phenyllithium.

Other anionic initiators include alkylmagnesium halide compounds such asbutylmagnesium bromide and phenylmagnesium bromide. Still other anionicinitiators include organosodium compounds such as phenylsodium and2,4,6-trimethylphenylsodium. Also contemplated are those anionicinitiators that give rise to di-living polymers, wherein both ends of apolymer chain are living. Examples of such initiators include dilithioinitiators such as those prepared by reacting 1,3-diisopropenylbenzenewith sec-butyllithium. These and related difunctional initiators aredisclosed in U.S. Pat. No. 3,652,516, which is incorporated herein byreference. Radical anionic initiators may also be employed, includingthose described in U.S. Pat. No. 5,552,483, which is incorporated hereinby reference.

In particular embodiments, the organolithium compounds include a cyclicamine-containing compound such as lithiohexamethyleneimine. These andrelated useful initiators are disclosed in the U.S. Pat. Nos. 5,332,810,5,329,005, 5,578,542, 5,393,721, 5,698,646, 5,491,230, 5,521,309,5,496,940, 5,574,109, and 5,786,441, which are incorporated herein byreference. In other embodiments, the organolithium compounds includelithiated alkylthioacetals such as 2-lithio-2-methyl-1,3-dithiane. Theseand related useful initiators are disclosed in U.S. Publ. Nos.2006/0030657, 2006/0264590, and 2006/0264589, which are incorporatedherein by reference. In still other embodiments, the organolithiumcompounds include alkoxysilyl-containing initiators, such as lithiatedt-butyldimethylpropoxysilane. These and related useful initiators aredisclosed in U.S. Publ. No. 2006/0241241, which is incorporated hereinby reference.

In one or more embodiments, the anionic initiator employed istrialkyltinlithium compound such as tri-n-butyltinlithium. These andrelated useful initiators are disclosed in U.S. Pat. Nos. 3,426,006 and5,268,439, which are incorporated herein by reference.

The amount of the vinyl organophosphine copolymerized with theconjugated diene may be described with reference to the conjugated dienemonomer. In one or more embodiments, the mole ratio of the vinylorganophosphine to the conjugated diene monomer may be at least0.0002:1, in other embodiments at least 0.001:1, and in otherembodiments at least 0.005:1. In these or other embodiments, the moleratio of the vinyl organophosphine to the conjugated diene monomer maybe at most 1:1, in other embodiments at most 0.05:1, and in otherembodiments at most 0.01:1. In one or more embodiments, the mole ratioof the vinyl organophosphine to the conjugated diene monomer may be fromabout 0.0002:1 to about 1:1, in other embodiments from about 0.001:1 toabout 0.05:1, and in other embodiments from about 0.005:1 to about0.01:1.

The amount of the copolymerizable monomer (e.g., vinyl aromatic)employed in practice of the present invention may be described withreference to the conjugated diene monomer. In one or more embodiments,the weight ratio of the copolymerizable monomer (e.g., vinyl aromatic)to the conjugated diene monomer may be at least 0:1, in otherembodiments at least 0.05:1, in other embodiments at least 0.1:1, and inother embodiments at least 0.2:1. In these or other embodiments, theweight ratio of the copolymerizable monomer (e.g., vinyl aromatic) tothe conjugated diene monomer may be at most 1:1, in other embodiments atmost 0.8:1, and in other embodiments at most 0.6:1. In one or moreembodiments, the weight ratio of the copolymerizable monomer (e.g.,vinyl aromatic) to the conjugated diene monomer may be from about 0.05:1to about 1:1, in other embodiments from about 0.1:1 to about 0.8:1, andin other embodiments from about 0.2:1 to about 0.6:1.

In one or more embodiments, the amount of anionic initiator (e.g., analkyllithium compound) may be varied from about 0.05 to about 100 mmol,in other embodiments from about 0.1 to about 50 mmol, and in still otherembodiments from about 0.2 to about 5 mmol per 100 gram of monomer.

As with the previous embodiments, the polymerization may be conducted insolution. Also, the polymerization may be conducted in the presence of arandomizer. And, the polymerization system may be the same as describedabove.

Regardless of the polymerization technique used, the introduction of therespective monomer (i.e., the conjugated diene monomer, the vinylorganophosphine monomer, and/or the vinyl aromatic monomer) may beaccomplished by employing several techniques. In one embodiment, such aswhere a batch polymerization is conducted, a mixture of the respectivemonomer may be prepared, and the polymerization initiator may besubsequently charged to the mixture. In other embodiments, such as wherea semi-batch polymerization technique is employed, the polymerizationinitiator may be charged to a reactor followed by the addition ofmonomer. The monomer may be charged by providing a blend of therespective monomer (e.g., a blend of conjugated diene monomer, vinylorganophosphine monomer, and optionally vinyl aromatic monomer). In oneor more embodiments, this blend of monomer can be sequentially chargedto the reactor in the form of two or more monomer charges. In otherembodiments, one or more of the monomer can be separately charged to thereactor either simultaneously or sequentially with respect to the othermonomer. For example, when using semi-batch techniques, a blend ofconjugated diene monomer and vinyl aromatic monomer can be charged tothe reactor, and the vinyl organophosphine monomer can be separatelycharged, either simultaneously with the conjugated diene monomer andvinyl aromatic monomer or sequentially during the course of thepolymerization.

In those embodiments where there is a desire to concentrate thephosphorus-containing mer units at the tail end of the polymer, thevinyl organophosphine monomer can be sequentially charged to the reactorfollowing completion or substantial completion of the polymerization ofthe conjugated diene monomer and optional vinyl aromatic monomer. In asimilar fashion, when using continuous polymerization techniques, thevinyl organophosphine monomer can be separately added to the continuousreactor or at a downstream location where polymerization of the monomerwill cause the vinyl organophosphine monomer to polymerize and providephosphorus-containing mer units at or near the terminal end of thepolymer.

As with the previous embodiments, the copolymer produced by polymerizingthe vinyl organophosphine with conjugated diene may beend-functionalized. Also, the copolymer may be quenched and isolated asdescribed above.

Copolymer Product

While practice of these embodiments are believed to react to producenovel functionalized polymers (i.e., polymers with aphosphorus-containing group), the exact chemical structure of thefunctionalized polymer produced in every embodiment may not be knownwith any great degree of certainty.

In one or more embodiments, the process of the present inventionproduces copolymers having one or more mer units defined by the formulaVII:

where R¹¹ and R¹² are each independently monovalent organic groups, orwhere R¹¹ and R¹² join to form a divalent organic group, and where R¹³,R¹⁴, and R¹⁵ are each independently hydrogen or monovalent organicgroups, or where R¹³ and R¹⁴ join to form a divalent organic group. Inparticular embodiments, R¹³, R¹⁴, and R¹⁵ are hydrogen atoms. Inparticular embodiments, R¹³, R¹⁴, and R¹⁵ are hydrogen atoms. As theskilled person will understand, R¹¹, R¹², R¹³ R¹⁴, and R¹⁵ derive fromR¹¹, R¹², R¹³ R¹⁴, and R¹⁵ of the vinyl organophosphine of formula I.

In one or more embodiments, the process of the present inventionproduces copolymers having one or more mer units defined by the formulaVIII:

where R¹¹ and R¹² are each independently monovalent organic groups, orwhere R¹¹ and R¹² join to form a divalent organic group, and where R¹³,R¹⁴, and R¹⁵ are each independently hydrogen or monovalent organicgroups, or where R¹³ and R¹⁴ join to form a divalent organic group. Inparticular embodiments, R¹³, R¹⁴, and R¹⁵ are hydrogen atoms. Inparticular embodiments, R¹³, R¹⁴, and R¹⁵ are hydrogen atoms. As theskilled person will understand, R¹¹, R¹², R¹³ R¹⁴, and R¹⁵ derive fromR¹¹, R¹², R¹³ R¹⁴, and R¹⁵ of the vinyl organophosphine of formula I.

In one or more embodiments, the copolymers also include mer unitsderiving from the polymerization of conjugated diene monomer andoptionally mer units deriving from the polymerization of monomercopolymerizable therewith (e.g., vinyl aromatic monomer, such as styrenemonomer). As suggested from the discussion of the polymerizationprocedure set forth above, these copolymers may include at least 60%, inother embodiments at least 80%, in other embodiments at least 90%, inother embodiments at least 95%, in other embodiments at least 97%, inother embodiments at least 99%, and in other embodiments at least 99.5%of their mer units, on a mole basis, deriving from conjugated dienemonomer or copolymerizable monomer other than the vinyl organophosphinemonomer (e.g., styrene), with the balance includingphosphorus-containing mer units deriving from the polymerization ofvinyl organophosphine monomer. Stated another way, the copolymers of oneor more embodiments may include up to 10 mole percent, in otherembodiments up to 5 mole percent, in other embodiments up to 3 molepercent, in other embodiments up to 1 mole percent, in other embodimentsup to 0.5 mole percent, and in other embodiments up to 0.25 mole percentmer units that are phosphorus-containing mer units deriving from thepolymerization of vinyl organophosphine monomer.

For ease of description, the mer units deriving from the polymerizationof the vinyl organophosphine may be referred to as phosphorus-containingmer units. In one or more embodiments, the phosphorus-containing merunits may be irregularly distributed along the backbone of the polymerchain among mer units deriving from the polymerization of conjugateddiene monomer (which may be referred to as diene mer units) as well asmer units deriving from the polymerization of copolymerizable monomersuch as units deriving from the polymerization of vinyl aromatic monomer(which may also be referred to as vinyl aromatic mer units). As theskilled person understands, polymers in which the mer units areirregularly distributed along the backbone may be referred to asstatistical copolymers. In particular embodiments, these irregularlydistributed mer units may be randomly distributed mer units. In yetother embodiments, the phosphorus-containing mer units may be in theform of blocks. In one or more embodiments, these blocks may be referredto as microblocks, which include blocks of about 3 to about 10 merunits. In other embodiments, these blocks may be referred to asmacroblocks, which include blocks including greater than 10 mer units.

In one or more embodiments, practice of the present inventionadvantageously produces polymer having a relatively high percentage ofphosphorus-containing groups located at the terminus of the polymerchain. In one or more embodiments, the copolymers of the presentinvention may include at least 1, in other embodiments at least 2, inother embodiments at least 3, in other embodiments at least 10, and inother embodiments at least 50 phosphorus-containing mer units located ator near the terminus of the polymer chain, where near the terminus ofthe polymer chain refers to 5 mole percent of the polymer adjacent tothe location where the polymer is quenched or terminated. In these orother embodiments, the copolymer includes from about 1 to about 100, inother embodiments from about 2 to about 75, and in other embodimentsfrom about 30 to about 50 phosphorus-containing mer units at or near theterminus of the polymer.

In one or more embodiments, where the phosphorus-containing groups arelocated at the terminus of the polymer chain, the polymer may be definedby the Formula IX:

where π is a polymer chain, α is a hydrogen atom or functional group,and x is an integer from 1 to about 100.

In other embodiments, where the phosphorus-containing groups are locatedat the terminus of the polymer chain, the polymer may be defined by theFormula X:

where Ti is a polymer chain, α is a hydrogen atom or functional group,and x is an integer from 1 to about 100. For purposes of Formulas IX andX, reference may be made to R¹¹— R¹⁵ as described above, and referencemay be made to the polymer chain π described above. In addition, thepolymer chain π may include copolymers including one or morephosphorous-containing mer units, as described above.

In one or more embodiments, the copolymers of the present invention maybe characterized by a number average molecular weight (Mn) of at least1, in other embodiments at least 5, and in other embodiments at least 20kg/mole. In these or other embodiments, the copolymers of the presentinvention may be characterized by an Mn of at most 10,000, in otherembodiments at most 5,000, and in other embodiments at most 500 kg/mole.In one or more embodiments, the copolymers of the present invention maybe characterized by an Mn of from about 1 to about 10,000, in otherembodiments from about 5 to about 5,000, and in other embodiments fromabout 20 to about 500 kg/mole.

In one or more embodiments, the copolymers of the present invention maybe characterized by a weight average molecular weight (Mw) of at least1, in other embodiments at least 7, and in other embodiments at least 30kg/mole. In these or other embodiments, the copolymers of the presentinvention may be characterized by an Mw of at most 10,000, in otherembodiments at most 5,000, and in other embodiments at most 500 kg/mole.In one or more embodiments, the copolymers of the present invention maybe characterized by an Mw of from about 1 to about 10,000, in otherembodiments from about 7 to about 5,000, and in other embodiments fromabout 30 to about 500 kg/mole.

The copolymers of the present invention may be characterized by amolecular weight distribution (i.e., polydispersity) of less than 2, inother embodiments less than 1.5, and in other embodiments less than 1.3.In one or more embodiments, the conjugated diene mer units of thecopolymers of the present invention may be characterized by a vinylcontent of at least 15%, in other embodiments at least 20%, and in otherembodiments at least 22%, on a mole basis. In these or other embodimentsthe vinyl content is from about 8 to about 80, in other embodiments fromabout 10 to about 70, and in other embodiments from about 15 to about 65mole percent. In these or other embodiments, the conjugated diene merunits of the copolymers of the present invention may be characterized bya 1,4-trans microstructure of from about 40 to about 75, in otherembodiments from about 45 to about 70, and in other embodiments fromabout 48 to about 65 mole percent. In these or other embodiments, theconjugated diene mer units of the copolymers of the present inventionmay be characterized by a 1,4-cis microstructure of from about 10 toabout 60, in other embodiments from about 15 to about 55, and in otherembodiments from about 20 to about 50 mole percent.

I. Use in Tires

The polymers and copolymers of this invention are particularly useful inpreparing tire components. In particular embodiments, these tirecomponents include silica filler. These tire components can be preparedby using the copolymers alone or together with other rubbery polymers(i.e., polymers that can be vulcanized to form compositions possessingelastomeric properties). Other rubbery polymers that may be used includenatural and synthetic elastomers. The synthetic elastomers typicallyderive from the polymerization of conjugated diene monomers. Theseconjugated diene monomers may be copolymerized with other monomers suchas vinyl-substituted aromatic monomers. Other rubbery polymers mayderive from the polymerization of ethylene together with one or moreα-olefins and optionally one or more diene monomers.

Useful rubbery polymers include natural rubber, synthetic polyisoprene,polybutadiene, polyisobutylene-co-isoprene, neoprene,poly(ethylene-co-propylene), poly(styrene-co-butadiene),poly(styrene-co-isoprene), and poly(styrene-co-isoprene-co-butadiene),poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene),polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber,epichlorohydrin rubber, and mixtures thereof. These elastomers can havea myriad of macromolecular structures including linear, branched andstar shaped. Other ingredients that are typically employed in rubbercompounding may also be added.

The rubber compositions may include fillers such as inorganic andorganic fillers. The organic fillers include carbon black and starch.The inorganic fillers may include silica, aluminum hydroxide, magnesiumhydroxide, clays (hydrated aluminum silicates), and mixtures thereof.

A multitude of rubber curing agents (also called vulcanizing agents) maybe employed, including sulfur or peroxide-based curing systems. Curingagents are described in Kirk-Othmer, ENCYCLOPEDIA OF CHEMICALTECHNOLOGY, Vol. 20, pgs. 365-468, (3rd Ed. 1982), particularlyVulcanization Agents and Auxiliary Materials, pgs. 390-402, and A. Y.Coran, Vulcanization, ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING,(2nd Ed. 1989), which are incorporated herein by reference. Vulcanizingagents may be used alone or in combination.

Other ingredients that may be employed include accelerators, oils,waxes, scorch inhibiting agents, processing aids, zinc oxide, tackifyingresins, reinforcing resins, fatty acids such as stearic acid, peptizers,and one or more additional rubbers.

These rubber compositions are useful for forming tire components such astreads, subtreads, black sidewalls, body ply skins, bead filler, and thelike. Preferably, the functionalized polymers or copolymers are employedin tread and sidewall formulations. In one or more embodiments, thesetread formulations may include from about 10% to about 100% by weight,in other embodiments from about 35% to about 90% by weight, and in otherembodiments from about 50% to 80% by weight of the copolymer based onthe total weight of the rubber within the formulation.

In one or more embodiments, the vulcanizable rubber composition may beprepared by forming an initial masterbatch that includes the rubbercomponent and filler (the rubber component optionally including thefunctionalized polymer or copolymer of this invention). This initialmasterbatch may be mixed at a starting temperature of from about 25° C.to about 125° C. with a discharge temperature of about 135° C. to about180° C. To prevent premature vulcanization (also known as scorch), thisinitial masterbatch may exclude vulcanizing agents. Once the initialmasterbatch is processed, the vulcanizing agents may be introduced andblended into the initial masterbatch at low temperatures in a finalmixing stage, which preferably does not initiate the vulcanizationprocess. For example, the vulcanizing agents may be introduced at atemperature less than 140° C., in other embodiments less than 120° C.,and in other embodiments less than 110° C. Optionally, additional mixingstages, sometimes called remills, can be employed between themasterbatch mixing stage and the final mixing stage. Various ingredientsincluding the functionalized polymer of this invention can be addedduring these remills. Rubber compounding techniques and the additivesemployed therein are generally known as disclosed in The Compounding andVulcanization of Rubber, in Rubber Technology (2nd Ed. 1973).

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested. The examples shouldnot, however, be viewed as limiting the scope of the invention. Theclaims will serve to define the invention.

EXAMPLES Sample 1. Control Non-Functional Polymer

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.55 kg hexanes, 0.39 kg 35.0 wt % styrene in hexanes,and 2.50 kg 21.8 wt % 1,3-butadiene in hexanes. To the reactor wascharged 3.44 mL of 1.65 M n-butyl lithium in hexanes, 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 87° C. Approximately 30 minutes after exotherm, aportion of the contents were discharged into isopropanol containingantioxidant (BHT). The polymer was drum dried to yield a polymer withproperties listed in Table 1.

Sample 2. Synthesis of SBR Initiated with the Butyl Lithium Adduct toVinyldiphenylphosphine

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.55 kg hexanes, 0.39 kg 35.0 wt % styrene in hexanes,and 2.50 kg 21.8 wt % 1,3-butadiene in hexanes. To the reactor wascharged a premixed solution (which is bright yellow in color) of 3.44 mLof 1.65 M n-butyl lithium in hexanes, 4.36 mL of 1.17 Mvinyldiphenylphosphine in hexanes, and 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 88.3° C. Approximately 135 minutes after exotherm,part of the contents were discharged into isopropanol containingantioxidant (BHT). The polymer was drum dried to yield a polymer withproperties listed in Table 1.

Sample 3. Synthesis of SBR Initiated with the Butyl Lithium Adduct toVinyldiphenylphosphine and Terminated with Chlorodiphenylphosphine

A portion of the contents from the polymerization in Sample 2 weredischarged into nitrogen purged bottles and terminated with 1 equivalentof chlorodiphenylphosphine/BuLi. The polymer was coagulated inisopropanol containing antioxidant and drum dried to yield a polymerwith properties listed in Table 1.

Sample 4. Synthesis of SBR Initiated with the Butyl Lithium Adduct to 2Equivalents of Vinyldiphenylphosphine

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.50 kg hexanes, 0.39 kg 35.0 wt % styrene in hexanes,and 2.56 kg 21.3 wt % 1,3-butadiene in hexanes. To the reactor wascharged a premixed solution (which is bright yellow in color) of 3.44 mLof 1.65 M n-butyl lithium in hexanes, 9.69 mL of 1.17 Mvinyldiphenylphosphine in hexanes, and 3.54 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 84.4° C. Approximately 30 minutes after exotherm, partof the contents were discharged into isopropanol containing antioxidant(BHT). The polymer was drum dried to yield a polymer with propertieslisted in Table 1.

TABLE 1 Analytical Properties of Polymers M_(n) M_(w) % Vinyl Phos- %Sam- (kg/ (kg/ T_(g), Styrene, (BD = phorus Function- ple mol) mol) ° C.wt % 100%) (ppm) ality 1 117.1 123.4 −36.0 20.6 54.6 2 0.7 2 121.3 133.7−32.9 22.5 51.7 196 76.9 3 117.6 128.4 −32.9 22.5 51.7 408 77.4 4 128.5200.5 −30.2 21.4 58.0 348 69.3

M_(n) and M_(w) were measured using GPC with polystyrene standards.T_(g) was measured using DSC. Styrene weight percent and vinyl contentwere determined using proton NMR. Phosphorus content was determined byusing ICP (inductively coupled plasma); the reported functionality wascalculated by ppm phosphorus found divided by theoretical ppm phosphorustimes 100%. Theoretical phosphorus was calculated based upon phosphorusatoms in the polymer multiplied by phosphorus molecular weight dividedby M_(n) times 1,000,000.

Compounds 1A-3A. Compounding of Polymers in all Carbon Black Formulation

The formulations of the compound mixtures are presented in Table 2 inweight parts. Each rubber compound was prepared in two portions namedinitial (masterbatch) and final. In the initial part, the polymer fromSamples 1-3 was mixed with carbon black, an antioxidant, stearic acid,wax, aromatic oil, and zinc oxide.

TABLE 2 Ingredients Masterbatch Synthetic Polymer 100 Carbon Black 55Wax 1 Antioxidant 0.95 Zinc Oxide 2.5 Stearic Acid 2 Aromatic Oil 10Total 171.45 Final Sulfur 1.3 Accelerators 1.9 Total 174.65

The initial portion of the compound was mixed in a 65 g Banbury mixeroperating at 60 RPM and 133° C. First, polymer was placed in the mixer,and after 0.5 minutes, the remaining ingredients except the stearic acidwere added. The stearic acid was then added after 3 minutes. Theinitials were mixed for 5-6 minutes. At the end of mixing thetemperature was approximately 165° C. The sample was transferred to amill operating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The finals were mixed by adding the initials and the curative materialsto the mixer simultaneously. The initial mixer temperature was 65° C.and it was operating at 60 RPM. The final material was removed from themixer after 2.25 minutes when the material temperature was between100-105° C. The finals were sheeted into Dynastat buttons and15.2×15.2×0.19 cm sheets. The samples were cured at 171° C. for 15minutes in standard molds placed in a hot press. The results of thevarious tests performed are reported in Table 3. Testing was conductedin a manner similar to that reported above.

TABLE 3 Physical Properties of Compounded Stocks Compound CompoundCompound Property 1A (Control) 2A 3A ML₁₊₄ (130° C.) 20.2 25.7 26.7 200%Modulus @ 23° C. (MPa) 8.25 8.35 8.13 T_(b) @ 23° C. (MPa) 15.8 14.912.60 E_(b) @ 23° C. (%) 335 314 276 tan δ 5% γ, 50° C. 0.224 0.1940.180 ΔG′ (50° C.) (MPa) 3.420 2.360 1.800 tan δ 0.5% γ, 0° C. 0.3980.399 0.406

The Mooney viscosities (ML₁₊₄) of the polymer samples were determined at100° C. by using a Monsanto Mooney viscometer with a large rotor, aone-minute warm-up time, and a four-minute running time.

The tensile mechanical properties were measured using the standardprocedure described in the ASTM-D 412 at 25° C. and 100° C. The tensiletest specimens had dumbbell shapes with a thickness of 1.9 mm. Aspecific gauge length of 25.4 mm is used for the tensile test.

Temperature sweep experiments were conducted with a frequency of 10 Hzusing 0.5% strain for temperature ranging from −100° C. to −10° C., and2% strain for the temperature ranging from −10° C. to 100° C. G′ is thestorage modulus measured at 10 Hz and 5% strain at 50° C. Payne Effect(ΔG′) was estimated from the change in G′ obtained from the strain sweepanalysis conducted at a frequency of 1 Hz at 50° C. with strain sweepingfrom 0.25% to 14.00% using a Rheometric Dynamic Analyzer (RDA).

Compounds 1B-4B. Compounding of Polymers in all Silica Formulation

The formulations of the compound mixtures are presented in Table 4 inweight parts. Each rubber compound was prepared in three portions namedinitial (masterbatch), remill and final. In the initial part, thepolymer from Samples 1-4 was mixed with silica, an antioxidant, stearicacid, wax, oil, and zinc oxide.

TABLE 4 Ingredients Masterbatch Synthetic Polymer 80 Natural Rubber 20Silica 52.5 Wax 2 Antioxidant 0.95 Stearic Acid 2 Oil 10 Total 167.45Remill Silica 2.5 Silica Coupling Agent 5 Final Sulfur 1.5 Accelerators4.1 Zinc Oxide 1.5

The initial portion of the compound was mixed in a 65 g Banbury mixeroperating at 50 RPM and 133° C. First, polymer was placed in the mixer,and after 0.5 minutes, the remaining ingredients except the stearic acidwere added. The stearic acid was then added after 3 minutes. Theinitials were mixed for 5-6 minutes. At the end of mixing thetemperature was approximately 165° C. The sample was transferred to amill operating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The remills were mixed by adding the initials and silica and shieldingagent to the mixer simultaneously. The initial mixer temperature was133° C. and it was operating at 50 RPM. The initial material was removedfrom the mixer after 3.5 minutes when the material temperature wasbetween 145° C. and 150° C. The sample was transferred to a milloperating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The finals were mixed by adding the initials and the curative materialsto the mixer simultaneously. The initial mixer temperature was 65° C.and it was operating at 45 RPM. The final material was removed from themixer after 2.5 minutes when the material temperature was between100-105° C. The finals were sheeted into Dynastat buttons and15.2×15.2×0.19 inch sheets. The samples were cured at 171° C. for 15minutes in standard molds placed in a hot press. The results of thevarious tests performed are reported in Table 5. Testing was conductedin a manner similar to that reported above.

TABLE 5 Physical Properties of Compounded Stocks Compound 1B CompoundCompound Compound Property (Control) 2B 3B 4B ML₁₊₄ (130° C.) 15.5 21.623.5 53.3 200% Modulus 7.48 7.99 8.13 9.01 @ 23° C. (MPa) T_(b) @23° C.(MPa) 12.80 12.10 12.80 12.90 E_(b) @23° C. (%) 308 276 283 259 tan δ 5%γ, 50° C. 0.170 0.139 0.131 0.113 (Strain Sweep) ΔG′ (50° C.) (MPa)4.330 3.460 2.580 1.500 tan δ 0.5% γ, 0° C. 0.331 0.352 0.352 0.418(Temperature Sweep)

Continuous Polymerization of SBR Sample 5. Control Non-FunctionalPolymer

Polymerization was conducted in a 24.6 liter reactor with a 20 minuteresidence time. The reactor was filled with hexane and the jackettemperature was set at 88° C. The following ingredients were meteredinto the bottom of the reactor: 1) 3.0 kg/hr styrene/hexane blend (31.8%styrene), 2) 24.6 kg/hr butadiene/hexane blend (21.7% butadiene), 3) 8.6kg/hr hexane, 4) 0.39 kg/hr DTHFP/hexane (0.10 M DTHFP), 5) 7.2 cc/hr1,2-butadiene (20%), and 6) 0.35 kg/hr lithium initiator/hexane (0.125 Mlithium). An additional stream of 10.6 kg/hr butadiene/hexane blend(21.7% butadiene) was added at the midpoint of the reactor to minimizeblock styrene formation. Polymer cement was removed at the top of thereactor into a storage vessel. After about 1-1.5 hours of polymerizationtime, steady state was achieved with the top temperature of the reactorat 99° C. and the bottom temperature at 91° C. After another hour ofpolymerization, samples were taken at the top of the reactor,drum-dried, and had the following properties: 31 ML4, 2.0 sec t-80, and99.7% conversion (GC).

Sample 6. SBR Initiated with VDPP

Sample 6 was the same as Sample 5 with a couple of exceptions.Ingredient 4, DTHFP/hexane, was added at 0.37 kg/hr (0.10 M DTHFP). Anadditional ingredient, VDPP/hexane (0.18 kg/hr, 0.2 M VDPP) was mixedwith ingredients 3, 4, 5, and 6 and allowed to mix for about 14 minutesprior to entering the bottom of the reactor. Polymer properties forSample 6 were 33 ML4, 2.3 sec t-80, and 99.7% conversion.

TABLE 6 Analytical Properties of Polymers. Mn Mw Tg Styrene, % VinylSample (kg/mol) (kg/mol) C. wt % (BD = 100%) 5 94 215 −56.1 11.7 41.2 693 232 −56.1 11.7 41.2

Compounds 5-6. Compounding of Polymers in all Silica Formulation.

The polymer samples prepared above were used to make rubber formulations(i.e., compounds) that were prepared using ingredients and a multi-stagemixing procedure as outlined in Table 4.

The initial portion of the compound was mixed in a 65 g Banbury mixeroperating at 50 RPM and 133° C. First, polymer was placed in the mixer,and after 0.5 minutes, the remaining ingredients except the stearic acidwere added. The stearic acid was then added after 3 minutes. Theinitials were mixed for 5-6 minutes. At the end of mixing thetemperature was approximately 165° C. The sample was transferred to amill operating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The remills were mixed by adding the initials and silica and shieldingagent to the mixer simultaneously. The initial mixer temperature was133° C. and it was operating at 50 RPM. The initial material was removedfrom the mixer after 3.5 minutes when the material temperature wasbetween 145° C. and 150° C. The sample was transferred to a milloperating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The finals were mixed by adding the initials and the curative materialsto the mixer simultaneously. The initial mixer temperature was 65° C.and it was operating at 45 RPM. The final material was removed from themixer after 2.5 minutes when the material temperature was between100-105° C. The finals were sheeted into Dynastat buttons and 6×6×0.075inch sheets. The samples were cured at 171° C. for 15 minutes instandard molds placed in a hot press. The results of the various testsperformed are reported in Table 7.

TABLE 7 Physical Properties of Compounded Stocks. Compound 5 CompoundProperty (Control) 6 ML₁ ₊ ₄ (130° C.) 30.7 35.3 200% Modulus @23° C.7.265 7.342 (MPa) T_(b) @23° C (MPa) 11.6 11.6 E_(b) @23° C (%) 291287.349 tan δ 5% γ, 50° C. (Strain 0.1482 0.1419 Sweep) ΔG′ (50° C.)(MPa) 3.341 3.112 tan δ 0.5% γ, ° C. 0.2020 0.1950 (Temperature Sweep)* 

 G′=G′(0.25% γ) − G′(14.0% γ)

Sample 7. Control Non-Functional Polymer

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.54 kg hexanes, 0.37 kg 35.0 wt % styrene in hexanes,and 2.55 kg 21.7 wt % 1,3-butadiene in hexanes. To the reactor wascharged 3.44 mL of 1.65 M n-butyl lithium in hexanes, 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 87° C. Approximately 30 minutes after exotherm, aportion of the contents were discharged into isopropanol containingantioxidant (BHT). The polymer was drum dried to yield a polymer withproperties listed in Table 8.

The number average (Mn) and weight average (Mw) molecular weights of thepolymer samples were determined by gel permeation chromatography (GPC)using polystyrene standards adjusted using the Mark-Houwink constantsfor the polymer in question. The microstructure of the polymers wasdetermined by ¹HNMR spectroscopy using CDCl₃ as a solvent. Tg wasdetermined by cooling the polymer to −120° C. and heating the polymer at10° C./min; the Tg was recorded as the midpoint between onset and endpoint.

Sample 8. SBR End-Capped with 1 Eq Vinyldiphenylphosphine

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.48 kg hexanes, 0.37 kg 35.0 wt % styrene in hexanes,and 2.59 kg 21.3 wt % 1,3-butadiene in hexanes. To the reactor wascharged 3.44 mL of 1.65 M n-butyl lithium in hexanes, 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 82° C. Approximately 30 minutes after exotherm, aportion of the contents were discharged into a dry, nitrogen purgedglass bottle and treated with 1 mol vinyldiphenylphospine per molpolymer. The polymer was coagulated in isopropanol containingantioxidant (BHT) and drum dried to yield a polymer with propertieslisted in Table 8.

Sample 9. SBR End-Capped with 2 Eq Vinyldiphenylphosphine

A portion of the polymer sample made in the reactor in Sample 8 wasdischarged into a dry, nitrogen purged glass bottle and treated with 2mol vinyldiphenylphosphine per mol polymer. The polymer was coagulatedin isopropanol containing antioxidant (BHT) and drum dried to yield apolymer with properties listed in Table 8.

Sample 10. SBR End-Capped with 3 Eq Vinyldiphenylphosphine

A portion of the polymer sample made in the reactor in Sample 8 wasdischarged into a dry, nitrogen purged glass bottle and treated with 3mol vinyldiphenylphosphine per mol polymer. The polymer was coagulatedin isopropanol containing antioxidant (BHT) and drum dried to yield apolymer with properties listed in Table 8.

TABLE 8 Polymer Mn Mw Styrene, % Vinyl Sample (kg/mol) (kg/mol) Tg, ° C.wt % (BD = 100%)  7 110.7 116.2 −36.6 20.1 53.4  8 108.5 117.0 −34.120.9 55.4  9 108.6 115.5 −34.1 20.9 55.4 10 107.9 115.1 −34.1 20.9 55.4

Compounds 7-10. Compounding of Polymers in all Silica Formulation.

The polymer samples prepared above were used to make rubber formulations(i.e., compounds) that were prepared using ingredients and a multi-stagemixing procedure as outlined in Table 4.

The initial portion of the compound was mixed in a 65 g Banbury mixeroperating at 50 RPM and 133° C. First, polymer was placed in the mixer,and after 0.5 minutes, the remaining ingredients except the stearic acidwere added. The stearic acid was then added after 3 minutes. Theinitials were mixed for 5-6 minutes. At the end of mixing thetemperature was approximately 165° C. The sample was transferred to amill operating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The remills were mixed by adding the initials and silica and shieldingagent to the mixer simultaneously. The initial mixer temperature was133° C. and it was operating at 50 RPM. The initial material was removedfrom the mixer after 3.5 minutes when the material temperature wasbetween 145° C. and 150° C. The sample was transferred to a milloperating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The finals were mixed by adding the initials and the curative materialsto the mixer simultaneously. The initial mixer temperature was 65° C.and it was operating at 45 RPM. The final material was removed from themixer after 2.5 minutes when the material temperature was between100-105° C. The finals were sheeted into Dynastat buttons and 15.24cm×15.24 cm×0.19 cm sheets. The samples were cured at 171° C. for 15minutes in standard molds placed in a hot press. The cured and uncuredproperties of the rubber compounds were tested for dynamic and/ormechanical properties, and the results of these tests are set forth inTable 9.

TABLE 9 Com- Compound Compound Compound pound Property 7 8 9 10 ML1 + 4(130° C.) 18.4 22.1 23.2 25.6 200% Modu- 7.93 8.12 8.22 8.29 lus @23° C.(MPa) T_(b) @23° C. (MPa) 10.5 14.7 13.7 13.7 E_(b) @23° C. (%) 247 306287 286 tan δ 5% γ, 60° C. 0.167 0.142 0.135 0.119 ΔG′ (60° C.) (MPa)*6.490 2.530 1.730 1.320 tan δ 0.5% γ, 0° C. 0.292 0.168 0.339 0.355 *ΔG′= G′(0.25% γ) − G′(14.0% γ)

Sample 11. Control Non-Functional Polymer

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.54 kg hexanes, 0.38 kg 35.0 wt % styrene in hexanes,and 2.53 kg 21.7 wt % 1,3-butadiene in hexanes. To the reactor wascharged 3.44 mL of 1.65 M n-butyl lithium in hexanes, 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 73.8° C. Approximately 30 minutes after exotherm, aportion of the contents were discharged into isopropanol containingantioxidant (BHT). The polymer was drum dried to yield a polymer withproperties listed in Table 10.

Sample 12. SBR Copolymerized with 0.9 Eq Vinyldiphenylphosphine PerPolymer and Terminated withN-1,3-(dimethylbutylidene)-3-(triethoxysilyl)-1-propylamine

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.44 kg hexanes, 0.38 kg 35.0 wt % styrene in hexanes,2.63 kg 20.9 wt % 1,3-butadiene in hexanes and 4.40 mL of 1.16 Mvinyldiphenylphosphine. To the reactor was charged 3.44 mL of 1.65 Mn-butyl lithium in hexanes, 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 79° C. Approximately 30 minutes after exotherm, aportion of the contents were discharged into a dry, nitrogen purgedglass bottle and treated with 0.9 molN-1,3-(dimethylbutylidene)-3-(triethoxysilyl)-1-propylamine per molpolymer. The polymer was coagulated in isopropanol containingantioxidant (BHT) and drum dried to yield a polymer with propertieslisted in Table 10.

Sample 13. SBR Copolymerized with 0.9 Eq Vinyldiphenylphosphine PerPolymer and Terminated with Isopropanol

A portion of the polymer sample made in the reactor in Sample 12 wasdischarged into isopropanol containing antioxidant (BHT) and drum driedto yield a polymer with properties listed in Table 10.

Sample 14. SBR Copolymerized with 2 Eq Vinyldiphenylphosphine PerPolymer and Terminated withN-1,3-(dimethylbutylidene)-3-(triethoxysilyl)-1-propylamine

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.44 kg hexanes, 0.38 kg 35.0 wt % styrene in hexanes,2.63 kg 20.9 wt % 1,3-butadiene in hexanes and 9.78 mL of 1.16 Mvinyldiphenylphosphine. To the reactor was charged 3.44 mL of 1.65 Mn-butyl lithium in hexanes, 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 82° C. Approximately 30 minutes after exotherm, aportion of the contents were discharged into a dry, nitrogen purgedglass bottle and treated with 0.9 molN-1,3-(dimethylbutylidene)-3-(triethoxysilyl)-1-propylamine per molpolymer. The polymer was coagulated in isopropanol containingantioxidant (BHT) and drum dried to yield a polymer with propertieslisted in Table 10.

Sample 15. SBR Copolymerized with 2 Eq Vinyldiphenylphosphine PerPolymer and Terminated with Isopropanol

A portion of the polymer sample made in the reactor in Sample 14 wasdischarged into isopropanol containing antioxidant (BHT) and drum driedto yield a polymer with properties listed in Table 10

Sample 16. SBR Copolymerized with 3 Eq Vinyldiphenylphosphine PerPolymer and Terminated withN-1,3-(dimethylbutylidene)-3-(triethoxysilyl)-1-propylamine

To a 7.57 L stainless steel reactor equipped with turbine agitatorblades was added 1.44 kg hexanes, 0.38 kg 35.0 wt % styrene in hexanes,2.63 kg 20.9 wt % 1,3-butadiene in hexanes and 14.66 mL of 1.16 Mvinyldiphenylphosphine. To the reactor was charged 3.44 mL of 1.65 Mn-butyl lithium in hexanes, 2.06 mL of 1.60 M2,2-ditetrahydrofurylpropane (DTHFP) in hexanes and the batch was heatedto an exotherm of 85° C. Approximately 30 minutes after exotherm, aportion of the contents were discharged into a dry, nitrogen purgedglass bottle and treated with 0.9 molN-1,3-(dimethylbutylidene)-3-(triethoxysilyl)-1-propylamine per molpolymer.

The polymer was coagulated in isopropanol containing antioxidant (BHT)and drum dried to yield a polymer with properties listed in Table 10.

Sample 17. SBR Copolymerized with 3 Eq Vinyldiphenylphosphine PerPolymer and Terminated with Isopropanol

A portion of the polymer sample made in the reactor in sample 16 wasdischarged into isopropanol containing antioxidant (BHT) and drum driedto yield a polymer with properties listed in Table 10.

TABLE 10 Mn Mw % Vinyl Phos- Average Polymer (kg/ (kg/ Styrene, (BD =phorus Phosphine/ Sample mol) mol) wt % 100%) (ppm) Chain 11 94.3 99.221.9 58.0 N/A 0 12 109.5 141.9 20.6 57.5 155 0.55 13 111.4 118.8 20.657.5 165 0.59 14 118.7 147.0 21.9 54.9 250 0.96 15 115.7 125.8 21.9 54.9310 1.16 16 109.0 138.7 20.6 50.8 580 2.03 17 109.8 120.2 20.6 50.8 3751.33

Compounds 11-17. Compounding of Polymers in all Silica Formulation.

The polymer samples prepared in Samples 11-17 were used to make rubberformulations using ingredients and a multi-stage mixing procedure asoutlined in Table 4 above.

The initial portion of the compound was mixed in a 65 g Banbury mixeroperating at 50 RPM and 133° C. First, polymer was placed in the mixer,and after 0.5 minutes, the remaining ingredients except the stearic acidwere added. The stearic acid was then added after 3 minutes. Theinitials were mixed for 5-6 minutes. At the end of mixing thetemperature was approximately 165° C. The sample was transferred to amill operating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The remills were mixed by adding the initials and silica and shieldingagent to the mixer simultaneously. The initial mixer temperature was133° C. and it was operating at 50 RPM. The initial material was removedfrom the mixer after 3.5 minutes when the material temperature wasbetween 145° C. and 150° C. The sample was transferred to a milloperating at a temperature of 60° C., where it was sheeted andsubsequently cooled to room temperature.

The finals were mixed by adding the initials and the curative materialsto the mixer simultaneously. The initial mixer temperature was 65° C.and it was operating at 45 RPM. The final material was removed from themixer after 2.5 minutes when the material temperature was between100-105° C. The finals were sheeted into Dynastat buttons and 15.24cm×15.24 cm×0.19 cm sheets. The samples were cured at 171° C. for 15minutes in standard molds placed in a hot press. Also, using similarprocedures as set forth above, the cured and uncured rubber compoundswere tested for dynamic and/or mechanical properties, the results ofwhich are set forth in Table 11.

TABLE 11 Compound Compound Compound Compound Compound Compound CompoundProperty 11 12 13 14 15 16 17 ML1 + 4 (130° C.) 11.6 15.5 22.7 26 3650.2 66.9 Bound Rubber 15.0 56.8 16.3 59.9 27.3 67.2 38.7 tan δ 5% γ,60° C. 0.162 0.084 0.150 0.078 0.135 0.076 0.112 ΔG′ (60° C.) (MPa)*4.42 0.74 4.17 0.51 2.67 0.56 1.24 tan δ 0.5% γ, 0° C. 0.385 0.415 0.3600.407 0.361 0.309 0.315

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

What is claimed is:
 1. A process for preparing a copolymer including oneor more phosphorus-containing mer units, the process comprising:anionically polymerizing conjugated diene monomer, vinyl organophosphinemonomer, and optionally monomer copolymerizable therewith.
 2. Theprocess of claim 1, where the monomer copolymerizable therewith isstyrene.
 3. The process of claim 1, where the vinyl organophosphine isdefined by the formula I:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, and where R³, R⁴,and R⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group.
 4. The process ofclaim 3, where the vinyl organophosphine includes vinyldihydrocarbylphosphines,dihydrocarbyl(2,2-dihydrocarbyl-1-hydrocarbylvinyl)phosphines,dihydrocarbyl(2,2-dihydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbyl-1-hydrocarbylvinyl)phosphines, ordihydrocarbyl(1-hydrocarbylvinyl)phosphines.
 5. The process of claim 1,where said step of anionically polymerizing includes preparing a mixtureof the conjugated diene monomer, vinyl organophosphine monomer, andoptional monomer copolymerizable therewith, and subsequently charging apolymerization initiator to the mixture.
 6. The process of claim 1,where said step of anionically polymerizing includes charging apolymerization initiator to a reactor, and subsequently charging a blendof the conjugated diene monomer, vinyl organophosphine monomer, andoptionally monomer copolymerizable therewith to the reactor.
 7. Theprocess of claim 1, where said step of anionically polymerizing includescharging a polymerization initiator to a reactor and subsequentlycharging conjugated diene monomer and optionally vinyl aromatic monomerto the reactor, and then subsequently charging the vinyl organophosphinemonomer to the reactor.
 8. The process of claim 7, where said step ofcharging the vinyl organophosphine monomer to the reactor takes placeafter substantial completion of the polymerization of the conjugateddiene monomer and optional vinyl aromatic monomer.
 9. The process ofclaim 1, where said step of polymerizing takes place in an organicsolvent.
 10. The process of claim 1, further comprising the step offunctionalizing the polymer.
 11. A copolymer having one or morephosphorus-containing mer units defined by the formula VII:

where R¹¹ and R¹² are each independently monovalent organic groups, orwhere R¹¹ and R¹² join to form a divalent organic group, and where R¹³,R¹⁴, and R¹⁵ are each independently hydrogen or monovalent organicgroups, or where R¹³ and R¹⁴ join to form a divalent organic group. 12.The copolymer of claim 11, where the phosphorus-containing mer units areirregularly distributed along the backbone of the copolymer among merunits derived from the polymerization of conjugated diene monomer. 13.The copolymer of claim 11, where the phosphorus-containing mer units arerandomly distributed along the backbone of the copolymer among mer unitsderived from the polymerization of conjugated diene monomer.
 14. Thecopolymer of claim 11, where the phosphorus-containing mer units areconcentrated near the terminus of the polymer chain.
 15. The copolymerof claim 11, where the copolymer has a number average molecular weightof from about 1 to about 10,000 kg/mole.
 16. The copolymer of claim 15,where the copolymer has a molecular weight distribution that is lessthan
 2. 17. The copolymer of claim 16, where the copolymer includes merunits deriving from the polymerization of conjugated diene monomer, andwhere these mer units have a vinyl content of at least 15 mole percent.18. A copolymer having one or more phosphorus-containing mer unitsdefined by the formula VIII:

where R¹¹ and R¹² are each independently monovalent organic groups, orwhere R¹¹ and R¹² join to form a divalent organic group, and where R¹³,R¹⁴, and R¹⁵ are each independently hydrogen or monovalent organicgroups, or where R¹³ and R¹⁴ join to form a divalent organic group. 19.The copolymer of claim 18, where the phosphorus-containing mer units areirregularly distributed along the backbone of the copolymer among merunits derived from the polymerization of conjugated diene monomer. 20.The copolymer of claim 18, where the phosphorus-containing mer units arerandomly distributed along the backbone of the copolymer among mer unitsderived from the polymerization of conjugated diene monomer.
 21. Thecopolymer of claim 18, where the phosphorus-containing mer units areconcentrated near the terminus of the polymer chain.
 22. The copolymerof claim 18, where the copolymer has a number average molecular weightof from about 1 to about 10,000 kg/mole.
 23. The copolymer of claim 22,where the copolymer has a molecular weight distribution that is lessthan
 2. 24. The copolymer of claim 23, where the copolymer includes merunits deriving from the polymerization of conjugated diene monomer, andwhere these mer units have a vinyl content of at least 15 mole percent.25. A method for preparing a functionalized polymer, the methodcomprising: i. polymerizing conjugated diene monomer, optionallytogether with comonomer, using a phosphorus-containing organometalinitiator.
 26. The method of claim 25, where the phosphorus-containingorganometal initiator is defined by the formula II:

where M is a metal, R¹ and R² are each independently monovalent organicgroups, or where R¹ and R² join to form a divalent organic group, whereR³, R⁴, and R⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group, andwhere R⁶ is a bond or a divalent organic group.
 27. The method of claim26, where M is lithium.
 28. The method of claim 27, where R³, R⁴, and R⁵are each hydrogen atoms.
 29. The method of claim 26, where thephosphorus-containing organolithium compound is defined by the FormulaIV:

where M is a metal, R¹ and R² are each independently monovalent organicgroups, or where R¹ and R² join to form a divalent organic group, whereR³, R⁴, and R⁵ are each independently hydrogen or monovalent organicgroups, or where R³ and R⁴ join to form a divalent organic group, andwhere R⁶ is a bond or a divalent organic group. In particularembodiments, R³, R⁴, and R⁵ are hydrocarbyl groups.
 30. The method ofclaim 29, where M is lithium.
 31. The method of claim 29, where at leastone R³, R⁴, and R⁵ are is a hydrocarbyl group.
 32. The method of claim25, where the amount of initiator employed is from 0.05 to about 100mmole per 100 g of monomer.
 33. The method of claim 26, where R⁶ isdefined by the formula III:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, R³, R⁴, and R⁵are hydrocarbyl groups, and where R¹, R², R³, R⁴, and R⁵ are defined asabove, and x is an integer from 1 to
 19. 34. The method of claim 29,where R⁶ is defined by the formula III:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, R³, R⁴, and R⁵are hydrocarbyl groups, and where R¹, R², R³, R⁴, and R⁵ are defined asabove, and x is an integer from 1 to
 19. 35. A method for preparing apolymer, the method comprising: i. preparing an initiator by reacting avinyl organophosphine with an organometal compound; and ii. polymerizingconjugated diene monomer, optionally together with comonomer, byinitiating the polymerization of the monomer with the initiator.
 36. Themethod of claim 35, where the vinyl organophosphine is defined by theformula I:

here R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, and where R³, R⁴,and R⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group.
 37. The method ofclaim 35, where the organometal compound is defined by the formula MR⁷_(n), where M is a metal, R⁷ is a monovalent organic group, and n isequivalent to the valence of the metal.
 38. The method of claim 37,where the metal is lithium, and thereby the organometal compound is anorganolithium compound.
 39. The method claim 35, where the vinylorganophosphines is selected from the group consisting ofvinyldihydrocarbyl phosphines,dihydrocarbyl(2,2-dihydrocarbyl-1-hydrocarbylvinyl)phosphines,dihydrocarbyl(2,2-dihydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbylvinyl)phosphines,dihydrocarbyl(2-hydrocarbyl-1-hydrocarbyl)phosphines, anddihydrocarbyl(1-hydrocarbyl)phosphines.
 40. The method of claim 38,where the molar ratio of organolithium to vinyl organophosphine (Li/P)is from 0.1:1 to 20:1.
 41. The method of claim 35, where the monomer is1,3-butadiene and comonomer is styrene.
 42. A functionalized polymerdefined by the Formula V:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group.
 43. A functionalized polymer defined by theFormula VI:

where R¹ and R² are each independently monovalent organic groups, orwhere R¹ and R² join to form a divalent organic group, where R³, R⁴, andR⁵ are each independently hydrogen or monovalent organic groups, orwhere R³ and R⁴ join to form a divalent organic group, where R⁶ is abond or a divalent organic group, P is a phosphorus atom, π is a polymerchain, and ω is a hydrogen atom, a terminal functional group, or amultivalent coupling group.
 44. A vulcanizate comprising the curedproduct of the polymer of claims 42 and 43, wherein the vulcanizateincludes carbon black, silicon, or carbon black and silica.
 45. Afunctionalized polymer defined by the formula IX:

where π is a polymer chain, α is a functional group or hydrogen atom,R¹¹ and R¹² are each independently monovalent organic groups, or whereR¹¹ and R¹² join to form a divalent organic group, and where R¹³, R¹⁴,and R¹⁵ are each independently hydrogen or monovalent organic groups, orwhere R¹³ and R¹⁴ join to form a divalent organic group.
 46. Afunctionalized polymer defined by the formula X:

where π is a polymer chain, α is a functional group or hydrogen atom,R¹¹ and R¹² are each independently monovalent organic groups, or whereR¹¹ and R¹² join to form a divalent organic group, and where R¹³, R¹⁴,and R¹⁵ are each independently hydrogen or monovalent organic groups, orwhere R¹³ and R¹⁴ join to form a divalent organic group.